Image of Pista elongata Moore 1909

Description:

I'm not entirely sure this is not P. pacifica, although Light's describes that as living under rocks and this colony (shown in part in the blurry second photo) is tightly packed in a sandy patch in rocky intertidal. Update: After further review, in particular, description and image in Intertidal Invertebrates of CA, by Morris, Abbott and Haderlie, I feel confident in this ID.