Gloomy Nudibranch

''Tambja morosa'', also known as ''Tambja kushimotoensis'' or ''Gloomy Nudibranch'', is a species of sea slug, a dorid nudibranch, a shell-less marine gastropod mollusk in the subfamily Nembrothinae within the family Polyceridae.

This species is instead sometimes placed in the family Gymnodorididae.