Periaster sp.
Echinoid
Paleocene
Locatelli Formation
Santa Cruz Mountains, California, USA

58mm echinoid. Largest we have ever seen from this site.

Periaster is a genus of sea urchin better known from the Middle Cretaceous (Cenomanian) of France.  Its occurrence in the Paleocene of California seems hard to explain.

Here’s an echinoid for the collector who doesn’t have one from the Paleocene of California.