Disarticulated valves. Animal 26mm long. Dorset, England. April 2017.
From above, the exposed tegmentum of the head valve (i) is approximately semicircular and on the tail valve (viii) is approximately circular (apparent 2D shape varies with how the 3D valves are positioned).
The aragonite valves are substantial, but brittle and very easily broken (1) when not supported by the chiton’s powerful muscles.

KEY ID FEATURES : 01 Acanthochitona fascicularis