If you spend enough time beachcombing, you may eventually find something that looks like a small black or brown pouch with pointed corners.
It might be tangled in seaweed, lying among shells along the high-tide line, or dried into a curled leathery shape farther up the beach.
This unusual object is commonly called a mermaid’s purse.
Despite the whimsical name, it has nothing to do with mermaids.
A mermaid’s purse is an egg case produced by certain sharks and skates. The tough capsule protects a developing embryo until the young animal is ready to hatch.
All true skates reproduce by laying eggs, while only some shark species do. NOAA, for example, describes winter skate eggs as developing inside hard, leathery cases known as mermaid’s purses.
Finding one on the beach means you have discovered evidence of animals that may be living offshore even if you never see them while swimming.
🦈 Is a Mermaid’s Purse a Shark Egg?
Sometimes.
Some shark species reproduce by laying eggs enclosed in leathery capsules. This reproductive method is called oviparity.
NOAA notes that egg-laying sharks produce fertilized eggs enclosed in leathery pouches that are commonly called mermaid’s purses.
Catsharks are one familiar example.
Other shark species reproduce differently and give birth to live young, so not every shark produces a mermaid’s purse.
If you find an egg case, its shape can sometimes help determine whether it came from a shark or a skate.
🪽 Skates Produce Mermaid’s Purses Too
Skates are close relatives of sharks and rays.
They have flattened bodies and broad, winglike pectoral fins that give many species a kite-shaped appearance.
Unlike many rays, true skates lay eggs.
Those eggs develop inside protective cases that can eventually wash onto beaches after the young skate has hatched.
The Shark Trust notes that all true skates produce egg cases, while NOAA describes the leathery cases of species such as winter skates as mermaid’s purses.
In many parts of the world, the mermaid’s purses beachcombers encounter are skate egg cases.
👜 Why Is It Called a Mermaid’s Purse?
The nickname probably comes from the object’s pouchlike shape.
Many egg cases are roughly rectangular and look almost like a tiny leather wallet or purse.
The pointed horns or tendrils extending from the corners only make the object look stranger.
A dried case lying among seaweed can easily inspire imaginative names.
“Mermaid’s purse” has stuck as the common beachcombing term.
You may also see them called:
- Shark egg cases
- Skate egg cases
- Egg capsules
- Eggcases
All describe essentially the same protective structure, although shapes differ considerably among species.
🥚 What Is Inside a Mermaid’s Purse?
When the egg case is first laid, it contains a developing shark or skate embryo along with the nutrients needed for development.
The embryo obtains nourishment from a yolk sac.
As it develops, it gradually takes on the recognizable shape of a miniature shark or skate.
Eventually the young animal hatches from the case and begins life independently.
Depending on the species, development can take many months.
NOAA reports that winter skate eggs typically incubate for about 6 to 12 months before the young hatch. Some deep-water skate species can remain in egg cases much longer.
🦈 What Does a Baby Skate Look Like?
A newly hatched skate already resembles a miniature adult.
It has the broad flattened body, fins, tail, and other features characteristic of a skate.
The young animal does not receive parental care after hatching.
Its egg case has essentially served as a small protective nursery during development.
That makes a mermaid’s purse surprisingly sophisticated.
What looks like a simple leathery pouch contains the environment necessary for an embryo to develop for months before emerging into the sea.
🛡️ What Is a Mermaid’s Purse Made Of?
The case is tough, flexible, and leathery rather than brittle like a chicken egg.
The Shark Trust describes skate and shark egg cases as tough capsules that protect embryos while they develop.
The material is largely keratin-based—the same general type of structural protein found in things such as hair and nails.
That durability helps explain why empty cases can survive long enough to wash ashore.
Once they dry, they can become darker, smaller, more rigid, and more curled than they appeared underwater. NOAA notes that beached skate egg cases often change significantly as they dry.
📐 What Does a Mermaid’s Purse Look Like?
There is no single shape.
Different shark and skate species produce differently sized and shaped egg cases.
Skate cases are often rectangular with a pointed horn extending from each corner.
Some shark egg cases are narrower and may have long curly tendrils.
Colors usually range from tan or brown to very dark brown or black, particularly after the case has dried on the beach.
Size varies too.
Some are small enough to fit easily in the palm of your hand.
Others can be impressively large.
Those differences can allow experts—and eventually experienced beachcombers—to identify which animal produced the case.
📏 Why Do Mermaid’s Purses Have Horns?
Those pointed projections are functional.
Egg cases need to remain in a suitable place while the embryo develops.
Depending on the species, horns, tendrils, or other structures can help secure the case around seaweed, reef structure, or the seafloor.
The Shark Trust explains that egg cases may use curled tendrils, horns, or sticky filaments to help attach them to an underwater surface while the embryo develops.
A structure that looks decorative to us is really part of the egg’s anchoring system.
🌀 Why Do Some Egg Cases Have Curly Tendrils?
Long curly tendrils are particularly characteristic of some shark egg cases.
They can wrap around seaweed or other underwater structures and help prevent the egg from drifting away.
The Shark Trust notes that catshark egg cases commonly have long curled tendrils at their ends.
Skate cases tend to be more rectangular with prominent horns at their corners.
This gives beginners a useful identification clue.
Long curly tendrils suggest certain sharks.
Four obvious corner horns suggest a skate.
Exact species identification requires more detail.
🌊 Where Do Sharks and Skates Lay Their Egg Cases?
Egg-laying species usually deposit their cases in places where they have a reasonable chance of remaining protected while the embryo develops.
Depending on the species, that might include:
- Seaweed
- Kelp
- Rocky reef
- Sandy seafloor
- Gravel
- Other underwater structures
Some skates use very specific nursery areas.
NOAA research in Alaska has found concentrations of enormous numbers of skate egg cases in particular nursery grounds where slope, water temperature, oxygen, and other conditions are suitable for embryonic development.
So although the empty case eventually appears on your beach, its story probably began somewhere offshore.
🌊 Why Do Mermaid’s Purses Wash Up on Beaches?
After an animal hatches, the empty case may remain on the seafloor for some time.
Eventually waves and currents can loosen it.
Once detached, the relatively lightweight case can be transported toward shore.
Storms are particularly good at moving them.
NOAA notes that skate egg cases commonly wash onto beaches after storms, while the Shark Trust recommends searching after stormy weather because waves bring more seaweed and egg cases onto the shoreline.
That is one reason mermaid’s purses make such interesting post-storm beachcombing finds.
〰️ Look Along the Wrack Line
If you want to find a mermaid’s purse, the wrack line is one of the best places to search.
This is the band of seaweed, shells, driftwood, and other material deposited by previous waves and high tides.
Empty egg cases frequently become tangled in seaweed.
The Shark Trust identifies the strandline—the British term commonly used for this deposited material—as one of the best locations for finding them.
They camouflage surprisingly well.
A dark egg case mixed into brown seaweed may be only a few inches from your foot without catching your attention.
Once you know what shape to look for, they become much easier to spot.
🌬️ Check Higher on the Beach Too
A dried mermaid’s purse is extremely light.
Wind can blow it away from the waterline and toward the upper beach.
The Shark Trust recommends looking not only among fresh seaweed but also toward the back of the beach and around vegetation where lightweight dried cases can become trapped.
So if the wrack line looks unproductive, keep searching.
The case you want may have traveled much farther from the water than an ordinary seashell.
🌧️ Are Mermaid’s Purses Easier to Find After a Storm?
Often, yes.
Storm waves disturb seaweed and other material on the seafloor and transport it toward land.
Empty egg cases can be swept along with that debris.
A storm may also create a thick new wrack line containing material that was previously offshore.
Wait until dangerous conditions have passed before looking.
High surf, lightning, flooding, debris, and erosion can make a post-storm beach hazardous.
The mermaid’s purses will still be interesting once it is safe to search.
📅 What Time of Year Can You Find Them?
Potentially any time of year.
Exact reproductive seasons vary among species and locations, but empty egg cases can remain in the marine environment before eventually washing onto shore.
The Shark Trust’s long-running Great Eggcase Hunt reports that egg cases wash ashore throughout the year.
Recent weather and local species may therefore matter more than choosing one supposedly perfect month.
🔍 How Can You Tell Whether a Mermaid’s Purse Is Empty?
This is the most important thing to determine before doing anything with one.
An empty case generally has an opening where the young shark or skate emerged.
It may also look collapsed, dry, lightweight, or torn.
However, do not rely solely on whether it appears dried out.
Inspect the case carefully.
Hold it toward the light if appropriate and see whether anything appears to remain inside.
Do not cut an egg case open simply to investigate.
If you are unsure whether a developing animal is still present, treat it as occupied.
🐣 What If There Is a Baby Shark or Skate Inside?
A mermaid’s purse containing a developing embryo should not become a beach souvenir.
The Shark Trust recommends returning a live egg case to seawater or a deep rock pool and, where practical, positioning it so that it is less likely to wash straight back onto the beach.
If you are at a staffed park, aquarium area, marine reserve, or lifeguarded beach, you can also alert knowledgeable personnel.
Avoid repeatedly handling or squeezing the case.
The priority is the animal developing inside.
📸 Can You See the Embryo Through the Case?
Sometimes.
A freshly laid or water-filled case may be translucent enough under the right conditions for part of an embryo to be visible.
NOAA has published images of shark egg cases in which the developing animal can be seen inside.
A dried, weathered case found on the beach is usually much darker and harder to see through.
Never damage an occupied egg case simply to get a better view.
🤔 Is a Mermaid’s Purse Alive?
The case itself is not an independent animal.
It is the protective capsule surrounding the embryo.
If the embryo has already hatched, what remains is essentially an empty casing.
If an embryo is still inside, however, the egg case contains a living animal and should be treated accordingly.
This distinction matters when beachcombing.
An empty case can be fascinating biological evidence.
An occupied one is still a nursery.
🦈 Does Every Shark Lay a Mermaid’s Purse?
No.
Sharks have several reproductive strategies.
Some lay egg cases.
Others retain eggs within the body until the young hatch.
Still others provide embryos with nourishment through placenta-like connections and give birth to live pups.
NOAA describes multiple shark reproductive strategies, with only oviparous—or egg-laying—species producing the familiar leathery external egg cases.
So finding a mermaid’s purse tells you something immediately about the type of shark or skate that produced it.
🪽 Do Stingrays Lay Mermaid’s Purses?
Generally, no.
The everyday use of the words skate and ray can be confusing, especially because some animals called “rays” in common names are scientifically skates.
True skates lay eggs.
Many true rays, including familiar stingrays, give birth to live young.
The Shark Trust points out this naming confusion and emphasizes that true skates are egg layers whereas true rays generally produce live young.
So the rectangular egg case you find is much more likely to be from a skate or an egg-laying shark than from a typical stingray.
🐚 Is a Mermaid’s Purse the Same as a Whelk Egg Case?
No.
Whelks also produce unusual egg structures that commonly wash onto beaches, but they look very different.
Whelk egg cases often resemble a string or chain of flattened disks.
Each capsule can contain numerous developing snails.
A mermaid’s purse, by contrast, is generally a single leathery capsule associated with a shark or skate embryo.
Both are excellent beachcombing finds.
They simply come from completely different groups of animals.
🌿 Is It Just a Piece of Seaweed?
It is easy to make that mistake.
Dried egg cases are often dark brown, curled, and leathery.
They may be tangled directly into kelp or other wrack.
Look for a relatively organized structure.
Four horns, a rectangular central pouch, or long tendrils are clues that you are looking at an animal-produced egg case rather than vegetation.
Once you recognize one, you will probably start noticing them more frequently.
📏 Can You Identify the Species From the Egg Case?
Often, at least with a good regional guide.
Scientists and experienced beachcombers use several features:
- Overall length and width
- Shape of the central capsule
- Length and shape of the horns
- Presence or absence of tendrils
- Surface texture
- Side keels or flanges
- Curvature
- Location where it was found
Different species create surprisingly distinctive cases.
The Shark Trust’s Great Eggcase Hunt uses exactly these characteristics to help participants identify and record shark and skate species from washed-up cases.
🔬 Mermaid’s Purses Can Help Scientists
An empty egg case may look like nothing more than beach debris.
To researchers, it can provide useful information.
If many cases from a particular species are recorded along a coastline, scientists gain evidence that those animals occur in nearby waters.
Repeated observations can also help reveal geographic distribution and possible breeding areas.
The Shark Trust has operated its Great Eggcase Hunt citizen-science project since 2003, asking beachgoers to photograph, identify, and record washed-up cases.
Your strange beach find can therefore become a tiny scientific data point.
📱 Photograph It Before Moving It
If you find an egg case, take a photograph.
Photograph the entire case from above.
Include something for scale if possible.
Take close-ups of the horns, tendrils, and sides.
Record the beach and date.
Those details may make species identification much easier later.
A photograph also allows you to enjoy the discovery without necessarily removing anything from the beach.
📜 Can You Take a Mermaid’s Purse Home?
If you are completely certain an egg case is empty, whether you may collect it depends on the beach.
Some places allow collection of empty biological material.
National parks, wildlife refuges, marine reserves, state parks, and other protected areas may prohibit removing wildlife parts or other natural objects.
Do not assume that an empty egg case is automatically legal to take simply because the animal has hatched.
Check the rules for the specific shoreline.
When collection is prohibited—or you are not sure—photograph it and leave it where you found it.
🧒 Mermaid’s Purses Are Great Finds for Kids
For a child, finding a mermaid’s purse can transform a beach walk into a marine-biology lesson.
The strange shape invites questions immediately.
What made it?
Was there a shark inside?
Why does it have horns?
How did it reach the beach?
Use the discovery to explain that sharks and skates have many different ways of reproducing and that much of the ocean’s wildlife lives out of sight.
Children should still ask an adult before picking up unfamiliar beach objects.
Jellyfish, fishing hooks, sharp debris, and living marine animals may be mixed into the same wrack line.
⭐ What Should You Do If You Find a Mermaid’s Purse?
First, look carefully before handling it.
Determine whether the case appears empty.
If an embryo may still be inside, return the case gently to suitable seawater and avoid disturbing it further.
If it is clearly empty, photograph it.
Try identifying it from its size, shape, horns, and tendrils.
Record where and when you found it.
Check local rules before taking it from the beach.
And if you live somewhere covered by a citizen-science egg-case project, consider submitting the observation.
🌊 A Small Clue to Life Offshore
Most beachgoers will never see a wild skate swimming across the seafloor.
They may never encounter an egg-laying shark.
Yet those animals can leave evidence directly at our feet.
A dark leathery pouch tangled among seaweed may have spent months protecting a developing animal somewhere offshore.
Eventually the young shark or skate emerged.
The empty case was loosened from the seabed.
Currents carried it away.
Waves delivered it onto the beach.
And a beachcomber found it.
That is what makes a mermaid’s purse such a wonderful discovery.
It is not simply a strange object washed ashore.
It is a tiny piece of the life cycle of an animal living beyond the waves.
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