Bonellia viridis

Comment from expert, Richard Willan: This is a Proboscis Worm (phylum Echiura: family Bonelliidae), not a mollusc. Bonellia viridis is a tropical species, that hides in a burrow under coral during the day and extends its long bifurcated proboscis at night up to 30 cm. The animal in this photo has been completely removed from its burrow and its proboscis is the light green structure on the right half of the body. It is an active predator, grabbing passing soft-bodied invertebrates, including opisthobranchs, to feed upon. This individual is a female; the male is tiny and it lives in the same burrow as the female. The male rarely feeds and it serves largely to fertilise the female.