Purple sea urchin at Hopkins station. Look closely to spot parasitic worm
These are three of the dozens of Strongylocentrotus purpuratus (Purple Sea Urchin) I saw, some boring right into the rock. I saw three species of urchins at Salt Creek, and this is by far the most common.
This 6" Strongylocentrotus franciscanus (Red Sea Urchin) was one of three species I saw, but I only noticed two of this species.
This 3" Strongylocentrotus droebachiensis (Green Sea Urchin) was one of three urchin species I saw.