Not a great photo... but blue bands were clearly visible.
These hermit crabs were very common on the beach and were often found in black turban shells.
Hermit crab running out of bigger shell
Pagurus samuelis, the blueband hermit crab, is a species of hermit crab from the west coast of North America, and the most common hermit crab in California. It is a small species, with distinctive blue bands on its legs. It prefers to live in the shell of the black turban snail, and is a nocturnal scavenger of algae and carrion.