Lengths 11.2 mm & 6.7 mm compared with Leptochiton cancellatus (centre image) 8.6 mm.
L. cinerea has a lozenge pattern on its girdle that is unique to it in N.W. Europe (see 17 Lepidochitona cinerea). On very pale specimens it is very faint, but the experienced eye can often make out traces of it (1) while there is no pattern on the girdle of Leptochiton cancellatus (2).
Under a microscope, the dorsal surface of the girdle has densely packed rounded granules 09 Lepidochitona cinerea , while those on Leptochiton cancellatus are squarish scales with curled up tips.
L. cinerea has a beak on the posterior of valves ii to vii which overlaps the adjacent valve (3) , while L. cancellatus has no overlapping beak (4).
Other differentiating features in text of “similar species” at 01 Lepidochitona cinerea and below image 25 Lepidochitona cinerea COMPARISON
Llŷn, North Wales. March 2016.

KEY ID FEATURES and similar species at: 01 Lepidochitona cinerea