This what is known as a Mermaid's Purse - it is actually a skate egg case. A Skate is a small ray and they are often seen (or felt) in the water at our beach.
This does not have any official or unofficial name. I have always enjoyed these things though. They are like dust bunnies on the beach. Beach debris seems to get all rolled around into a little ball and they are all over the beach, just as the dog hair ones are all over my house.
1 day ago