Astrodapsis antiselli
Echinoid
Late Miocene
Santa Margarita Sandstone
San Luis Obispo County, California, USA

130mm x 110mm block with at least 6 echinoids. Average size 42mm.

Astrodapsis is a genus of extinct sea urchin from the Miocene to Pliocene of California and Mexico.

Many of the once easily-accessible sites for Astrodapsis in California have been built on or posted off-limits.  Clusters of them used to be common sights at shows.  Here’s a nice multiple for the California fossil collector or echinoid specialist to display.