This 2" Urticina crassicornis or Painted Anemone was the only one I found while looking over the edge of the docks today.
Small hard coral growing on the underside of a large float at the dock. About 1/2 inch high. See the following observation for photos of this in situ.
At Cabrillo Beach tide pools.
No idea what this is. It was hard, felt rough and calcified like coral. Not at all soft like sponge or tunicate, and tiny 'polyps' with dark centers and 'hairs' are visible. About 1" across and 1/2" high. Growing among tunicates on the underside of a float at the dock. Perhaps something introduced?
Anthozoa is a class within the phylum Cnidaria. Unlike other cnidarians, anthozoans do not have a medusa stage in their development. Instead, they release sperm and eggs that form a planula, which attaches to some substrate on which the cnidarian grows. Some anthozoans can also reproduce asexually through budding. More than 6,100 species have been described.