This is some sort of clam. It was buried in the sand but we dug it out of its burrow to see what it was.
It's about 2.5 cm long. It was alive so we couldn't see inside.
The burrow made a star shape in the sand.
No identification made yet.
No interactions present.
Can you add a few notes? Size is quite important. Edit/Description.
If you still have it or can find another, then a photo of the hinge area would help.
See here http://www.ispot.org.uk/node/296098
Lat/Lng: 53.7, -3.0
OS grid ref: SD3626