Slug 8 mm long, from the underside of a low intertidal cobble at El Tomatal, Baja California. The large pits in the sponge (Oscarella sp.) represent a night's feeding activity by the slug, and those are the slug's fecal strands on the surface of the sponge (left center). The 2nd image is of the same individual and was taken by @lemurdillo (Brenna Green). 4th image shows the specimen as originally found.

Hessam Ghanimi, working under Dr. Angel Valdes at Cal Poly Pomona, in 2018 completed his MS Thesis on Berthella, one chapter of which shows that what had been called B. stellata from around the world to be a complex of many species, one of which is confined to the Eastern Pacific and now called B. andromeda (see comment below). DNA sequenced from this specimen (CASIZ 182217A) was used in Hessam's phylogenetic analyses showing B. stellata to be a species complex.