It is a marine gastropod mollusc in the family Goniodorididae.
This species was described from the Mediterranean Sea at Nice, France.
It has a wide distribution from there along the Atlantic coast to Norway, Greenland, Iceland and across to New England on the coast of North America.
Ancula pacifica apparently has a number of colour varieties which closely approach this species and is currently believed to be a synonym.
It has been reported to possibly feed on a variety of sessile organisms, but these are just the substratum to which the ectoprocts are attached.