Glorious Top Shell (Calliostoma gloriosum), photographed 2 April 2016
The northern geographic range limit for this species is often listed as San Francisco, but I've found several specimens — broken shells like this one — washed ashore in the Bodega Bay area during the last 12 years.
Glorious Top Shells are supposedly more common in deeper water, so perhaps they occur offshore, and it takes a lot of wave energy (like we've experienced this winter) to push them onto the beach?
P.S. Recently, I've shown two other top snails — Channeled Top Snail (Calliostoma canaliculatum) and Purple-ringed Top Snail (Calliostoma annulatum), but I have yet to show the most common top snail in this area, Blue Top Snail (Calliostoma ligatum). Some day!