I wrote in my dive book that there was a huge white christmas tree worm on this dive. I admit that this doesn't look much like a white worm.  The red must not have been visible in natural (pretty bluish, since this worm was at 50 feet) light.  This was a tame worm, too.  Normally you get one shot at these, unless you're willing to wait a few minutes for them to venture out again.  This one stayed out for six or seven exposures. 

Nikon F4, 200mm f/4D Auto Micro Nikkor,  Aquatica Housing, 2 Ikelite 200 strobes, f/16, Kodak Royal Gold 100.