The Rayed Trough Shell – Mactra stultorum (Linnaeus) – is a bivalved mollusc that is commonly found on sandy beaches, or at least the empty shells are frequently found. However, recently at Rhossili beach great numbers of this mollusc washed ashore with the animal still inside the shell. Unfortunately, most were dead or dying. Some unknown event had stirred up the seabed off shore and loosened them from the sediments before landing them on the beach. They lay where they had been naturally deposited: singly, in pairs, trios, quartets, quintets, or groups of a dozen or more. Overall, probably hundreds of thousands of Rayed Trough Shells covered the strandline as far as the eye could see.
This species has a broadly triangular, thin and brittle shell which is white, maybe with a hint of purple, growing up to 50 mm in length. The sides of the shell are smoothly curving. Light brown rays of varying width and depth of colour radiate from the umbones. Rayed Trough Shells live in clean sand of the lower shore down to the shallow sublittoral. They are widespread and abundant on most of the British coastline.
Revision of a post first published 17 April 2010
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