Found growing under dock at boat ramp, close-up detail on last photo
On Laminaria sp.
AKA Black-and-Red Encrusting Bryozoan, as per Lamb, p. 165.
This bright orange 2" circle is a colony of Schizoporella unicornis or Orange Encrusting Bryozoan. It's supposed to be quite common, but I don't remember ever seeing it before. It was growing on a rock that was visible during a minus tide.
The skeletal remains of a colony attached to a mussel shell.
One million bonus points if you can ID the microscopic white (possible baby Rostanga pulchra? Nudibranchs!?) on the left of this photo.
On giant kelp frond.
The Bryozoa, also known as Polyzoa, Ectoprocta or commonly as moss animals, are a phylum of aquatic invertebrate animals. Typically about 0.5 millimetres (0.020 in) long, they are filter feeders that sieve food particles out of the water using a retractable lophophore, a "crown" of tentacles lined with cilia. Most marine species live in tropical waters, but a few occur in oceanic trenches, and others are found in polar waters. One class lives only in a variety...