Iceland Cyprina "Arctica islandica" quahog Clam ? Atlantic Clam? Arctic Clam?
This could have reached 100 years of age.
They are a slow growing species and the subject of research. The shells can lie on the seabed for several thousand years. The shells have growth rings similar to tree rings and can indicate climatic conditions in the sea. This is 9.5 cm across, I have found a larger specimin. They can reach 13cms across and have only one natural predator (a catfish) due to their strong shells.
Found on Barmouth beach Wales
Taken 17th January 2012