English Channel to Mediterranean, to W. Africa. Herbivore and grazer in the upper infralittoral, in rocky environments. Mediterranean shells are characterized by a smaller size than in the Atlantic, a more lengthened shape, a larger variety of colours and patterns, a stronger spiral sculpture (grooves or plates, sometimes scales) and finally by the capacity to develop extremely pronounced radial folds or lamellae.

On rock, Paralia Mourtiás, Mortiá, SE. Magnesia, Thessalia, Greece. – Original picture provided by C. Taklis for iNaturalist – (CC BY). Notice, between the numerous tentacles, the small digiform epipodial projections (pale green). In the variant “mykonosenesis”, these projections are much bigger, and highly ramified.