Phyllodesmium is a genus of predatory sea slugs, aeolid nudibranchs, marine gastropod molluscs in the family Myrrhinidae.
[2] These nudibranchs occur in the tropical Indo-Pacific Ocean and warm temperate waters of Japan, Tasmania and South Africa.
[3] Some of the species are also unusual in that they are able to utilize zooxanthellae from their prey, in a symbiotic relationship that provides them with extra nutrition from photosynthesis, hence they are commonly called "solar-powered" sea slugs (also see the Sacoglossa).
They do not have cnidosacs, and thus they would in reality be palatable to eat for various predators, however they are almost all extremely well camouflaged, so that they resemble almost perfectly the soft coral on which they live and feed, not only in color but also in form.
This excellent camouflage also makes these nudibranchs difficult for humans to notice, and it is likely that several species in this genus have not yet been discovered, described, and named scientifically.