Mollusc looks like a set of teeth with gum disease!
Hi Colin, Your image shows Acanthochitona fascicularis - the wide fleshy girdle extending between the valves to the midline is diagnostic - no other Brit. sp. has the feature. If it were in water you would see 18 tufts of bristles. Have a look at the images (couple from Ireland & selection from Croatia) at http://www.conchsoc.org/spaccount/acanthochitona-fascicularis I am preparing images of L. asellus for upload onto the Conch soc site shortly.
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