Radula, 14 mm long, inside translucent white radular sac. From 42 mm long specimen. Dorset, England. April 2017.
The teeth are pale when initiated at the rear of the translucent, white radular sac (1).
They harden and darken to bright rust and black (2) as they are moved forwards along the radula and incrementally mineralized by the walls of the sac (3). The colour of the teeth becomes clearer where they emerge from the sac near the anterior (4).
Radula length 33% of body length.

KEY ID FEATURES : 01 Acanthochitona fascicularis