Length 26 mm. Llŷn, North Wales. March 2016.
Head and foot never protrude into view naturally on live chiton; can only be seen if animal removed from substrate, or placed on glass (as here). Most of head occupied by large transverse slit-mouth with wrinkled lips surrounded by large hood, no eyes or sensory tentacles.
1: mouth spread in contact with substrate.
2: mouth contracted away from substrate.
3: hood spread in contact with substrate.
4: hood crumpled away from substrate.

KEY ID FEATURES and similar species at: 01 Acanthochitona crinita