skate egg case

 

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These are the egg cases of a skate, a fish related to the stingray. The egg capsules are also called "mermaid's purse", "little mermaid's pocketbook" or "devil's purse". The pouches are made of keratin (similar to fingernails) and surrounds one embryo. The embryo is usually gone by the time the capsule washes up on the shore. Catsharks lay similar egg cases, but their cases usually have long, very curly horns, whereas the skate cases have shorter, thicker horns.