Phyllodesmium briareum

Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Order: Nudibranchia
Family: Myrrhinidae
Genus: Phyllodesmium
Species: Phyllodesmium briareum

Phyllodesmium briareum is a solar-powered aeolid nudibranch that lives on and mimics the soft coral Briareum. Its brownish-purple cerata look almost exactly like the coral's polyps.

It grows to about 3-4 cm and keeps symbiotic zooxanthellae from its coral prey alive in its body, gaining extra energy from their photosynthesis. It feeds only on Briareum and stays on its host.

In the Philippines it is found on Briareum colonies on shallow reefs, where it is easy to overlook among the swaying polyps.