Mermaid's Purses: What are they?

Despite the magical name, a mermaid's purse is not a treasure from folklore. It is the egg case of a skate or certain species of shark. Along the Western Cape coast, these remarkable egg cases are commonly produced by skates—cartilaginous fish closely related to sharks and rays.

Most beachcombers are familiar with the dried, black, leathery cases that often wash ashore long after their occupants have hatched. These are usually easy to miss, as they closely resemble dried hard kelp. This find was different. The egg case was still soft, moist, and intact. When held up to the sunlight, a pale shape could be seen inside, suggesting that it may still have contained a developing embryo. 

Even though I was unable to determine whether the occupant was alive, the decision was simple: return it to the sea as quickly as possible. I might just be saving a little life. 

What Exactly Is a Mermaid's Purse?
A mermaid's purse is a protective egg case made of collagen. Female skates deposit these cases on the seabed, often anchoring them to seaweed or other underwater structures. Inside, a young skate develops over several months before eventually hatching.

The four horn-like projections at the corners help distinguish many skate egg cases from those of some shark species.

Meet the Skate
Skates are fascinating fish that spend much of their lives on the ocean floor. Their flattened bodies and wing-like fins allow them to glide gracefully through the water or rest partially buried in sand.

Although they resemble stingrays, most skates do not possess a venomous tail spine. Like sharks, they have skeletons made of cartilage rather than bone.

Why Returning It Matters
Fresh egg cases occasionally become detached from their anchoring points during storms and strong swells. If an intact egg case still contains a developing embryo, returning it to the water may give it a chance to survive.

While it is impossible to know whether this particular occupant was alive, placing the egg case back into the ocean was the safest choice.

Keep Your Eyes Open
The beaches of De Kelders, Gansbaai, Franskraal, and Pearly Beach are wonderful places to discover marine treasures. The next time you spot a dark, leathery pouch among the kelp and shells, take a closer look—you may be holding one of the ocean's most remarkable nurseries.

And who knows? You might even have the opportunity to give a tiny skate a second chance at life.