At first Dan thought these where some for of Nudibranch or worm. But they're actually members of the sea cucumber family.

2003:09:05 15:18:59
Island: Rinja
Dive Site: Cannibal Rock
Speed: 1/30 sec
Aperture: f8.0
ISO: 64
Exposure Compensation: 0.0
Exposure Program: Aperture Priority
Focal Length: 7 mm (34 mm eq.)
Flash: -2