Mantle translucent cream to reddish brown, covered with irregular low ridges (enlarged inset on right). Often, but not always, there are many small opaque white marks and/or a large, central, dorsal, opaque white mark (Y, transverse bar or irregular blotch).
The mantle rim is not curved up to form an exhalant siphon, and its dorsal surface has no tentacles, gills or tubercles.
Mediterranean and north-eastern Atlantic as far north as Brittany. Records of it from elsewhere in the world have been segregated with DNA into several other species.

marinvert.senckenberg.science/image-browse/