Possible Cardiidae

[nharvey]

Hello,

I have been working through a range of shells I collected when I was a child in the 1960s. These have included foreign specimens acquired by my grandfather as well as shells that I picked up on the beach. The attached photos show three specimens that, originally, I thought were Cerastoderma edule - known in this country as the Edible Cockle. However, the shape of these shells is subquadrate with the beak far over the midline and the right hand corner flaring out. The other cockles I have are broadly ovate - the beak is still over the midline but the shell is rounder and more even. I realise that shells, like people, vary from specimen to specimen but I would be grateful if an expert eye could have a look and give their opinion as to what these might be. The shells could have been collected either in Pembrokeshire in south west Wales or in Norfolk on the east coast of England. Alternatively, they could come from anywhere in the world, if they were a part of my grandfather's gift, which I know is not much help!! The largest shell is 4.75cms wide, the smaller white shell is 3.5cms and the brown shell is 3cms wide.
Thanks