An exceptional low tide (-1.7 ft.) at Duxbury Reef in Bolinas, CA, on 25 November 2011 revealed many interesting marine invertebrates:
A Sunburst Anemone (Anthopleura sola) with unusual bright lime-green coloration.
The siphons of two different piddocks or rock-boring clams. Note the frilly openings to the inhalant siphons that act like sieves, allowing smaller particles through and keeping out larger particles.
Quite a few nudibranchs or sea slugs, including this colorful Sea-clown Nudibranch (Triopha catalinae). This species eats branching, arborescent bryozoans.
A peanut worm (Phascolosoma agassizii) searching among purple urchins (Strongylocentrotus purpuratus). This photo shows the striped introvert, or anterior portion of the worm; the peanut-shaped trunk, or main part of the body, is hidden from view.