Description: A large chiton, reaching up to 4 cm in length. It usually has a pink to chestnut brown colouration with white or fawn marbling on the shell plates, although colour can be highly variable. Shell plates are smooth and glossy. There may be distinct growth lines and some fine granulation. The girdle is wide and thin with a smooth leathery texture to naked eye and has a pink, or yellow colouration with brown, pink or purple banding or mottling.

Habitat: Lower shore and shallow sublittoral; found under boulders and rocks.

Distribution: Seems to be a northern species. Reported from east and north-east of the island of Ireland, and most records from Britain are concentrated in the northern areas. There are some records from southern England, although some of these may be confusions with B ruber.

Similar Species: Small individuals could be confused with Boreochiton ruber, however B. ruber ony reaches around 2 cm maximum. Could also be confused with Callochiton septemvalvis.

Key Identification Features:

• Large chiton, reaching up to 4 cm.
• Pink-brown colouration often with marbling.
• Wide, thin girdle with leathery texture.
• Girdle often pink or yellow with brown/pink/purple banding or mottling.

Distribution Map from NBN: Tonicella marmorea at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Tonicella marmorea at iNaturalist World Species Observations database.

GBIF data for Tonicella marmorea

WoRMS: Tonicella marmorea at World Register of Marine Species. Accepted name: Tonicella marmorea (O. Fabricius, 1780). AphiaID: 140151.

Classification: Biota; Animalia; Mollusca; Polyplacophora; Neoloricata; Chitonida; Acanthochitonina; Mopalioidea; Tonicellidae; Tonicellinae; Tonicella