big cockles

[Tengu]

On Luing i found a beach with huge cockles on (the mussels and limpets were big too)

one was 55mm across.

Im no shefish eater, but am curious,

would an example this size be tough to eat?

[Intertidal]

Shouldn't be.

Main thing with cockles is sand - they can be relatively slow to purge it.
I have a net bag for bivalves that I can hang in the water for, say. 24 hours before cooking them. even so theres usually some sand left.
Cockles are also incredible accumulators of nickel - not that that is likely to be a problem on Luing!

Intertidal