Caerulea Nudibranch

Found singly, or in pairs, on rubble, and sandy areas, of coral and rocky reefs.
They feed on sessile aquatic animals.
Indo-West Pacific - Indonesia

Opisthobranchia - Nudibranchs - Sea Slugs meaning "naked gills" are molluscs without a hard shell.
All opisthobranchs are hermaphrodites.
These beautiful slugs are usually brilliantly coloured and this in itself can act as a deterrent against predators. Some sea slugs secrete acid from stinging cells in their tentacles while others secrete acid from cells in their mantle.
Nudibranchs are slow moving, can swim or be propelled along either by muscular contraction or by millions of tiny hairs on the bottom of a fleshy 'foot', they have a voracious appetite and feed with a rasp like tongue.
Nudibranch lay their eggs in a ribbon effect on the sand, in different colours depending on species.