Chondrichthyes

An egg case or egg capsule, colloquially known as a mermaid's purse or devil's purse, is a casing that surrounds the fertilized eggs of some sharks, skates, and chimaeras. They are among the common objects which are washed up by the sea. Because they are lightweight, they are often found at the strandline, the farthest point of the high tide. This one was quite large, about 4X6 inches