"Mermaid’s purse” is a name often given to the olive to dark brown, horny egg cases of skates or rays. Female skates lay their eggs on offshore reefs and surround them with this distinctive, protective covering. There are five species of skates from our waters with egg cases of this general shape.
There are fingerlike projections on the underside that hold the case to the reef. Each case has up to seven developing little skates in it. Each one looks like a miniature adult with a large sack of yolk attached to its stomach by a tube. In heavy seas, these may be broken loose and the case washed ashore. Usually, by the time the case reaches the beach, the young have died.
This is not always the case though. Read how the aquarists at the Visitor Center hatched one of these egg cases and enjoy this video of the newborn skate swimming.
See original content in Flotsam, Jetsam and Wrack.