Disarticulated valves. Animal 16 mm long. Dorset, England. April 2017.
i: head valve.
ii to vii: intermediate valves.
viii: tail valve.
The tegmentum (1) , visible on the live animal, is a dorsal, sculptured, coloured layer of organic chitinous material and inorganic aragonite permeated by canals.
The articulamentum (2), concealed on the live animal, is a ventral layer of white, nacreous aragonite, permeated by canals only in the jugal tract (3) which is often black.

KEY ID FEATURES : 01 Acanthochitona fascicularis