With hermit crab.
AKA Pacific Gaper, as per siphon ID notes in Lamb & Hanby, p 198.
Big fellow, perhaps 4" carapace.
Lamb & Hanby, p. 73. Face up in strong current, no mucus.
Credit to dpom for taking this awesome photo with my iPhone.
Pillar Point Reef. Is that eggs/poo/??
Saw several with this white stuff (heavier than surrounding water) near it - does anyone know what this is? Sperm/eggs?