I have a Codakia orbicularis with the right valve measuring 56 mm and
the left 43 mm. Both valves are normal with no sign of damage. It was
collected dead but with both valves attached. Undoubtedly, the mantle on
one side was injured and stopped laying down shell, but how did it
survive long enough to continue growing on the other side with about 1/2
inch of its body exposed?

Bill Clendenin
Sarasota, Florida