Yellow Tube Sponge - Aplysina fistularis, Turneffe Island Atoll, Belize

Soft-walled tubes, usually in clusters joined at the base. Length of tubes up to 120 cm. In deeper water, the tubes tend to become longer than at shallow places. The surface is finely conulose and does not show the deep and meandering grooves of Aplysina lacunosa .

Source: http://species-identification.org/species.php?species_group=caribbean_diving_guide&id=436