Wikipedia
Plocamopherus
Plocamopherus is a genus of sea slugs, specifically nudibranchs, shell-less marine gastropod molluscs in the family Polyceridae, subfamily Triophinae. A unique character of Plocamopherus species is a globular bioluminescent organ at the tip of the pair of appendages which are placed just behind the gills. Many species are known to be nocturnal and several are from deep water. They feed on bryozoans.