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 (low center). The 2nd image is of the same individual and was taken by @lemurdillo (Brenna Green). 4th image shows the specimen as found.

Hessam Ghanimi, working under Dr. Angel Valdes at Cal Poly Pomona, last year completed his MS Thesis on Berthella, one chapter of which shows B. stellata from around the world to be a complex of many species, one of which is confined to the Eastern Pacific. Stayed tuned for the name changes.