Heads 1,2 & 4 from Dorset, England, 2017. Head 3 from Croatia, 2012 © Prkić.
The head lacks eyes and sensory tentacles. It consists of a large transverse slit-mouth with wrinkled lips (1), surrounded by a large hood (2). It is usually yellowish, sometimes orange or pinkish, and may be stained green (3) by the algae it feeds on. The ventral surface of the head (4, dead specimen), usually concealed against the foot, is whitish.

KEY ID FEATURES : 01 Acanthochitona fascicularis