Biologic evolution

It is a clam in Tokyo Bay.
It is a Meretrix meretrix that came to Waca last year.
Because what was put out from the water tank and dried had clearly
understood the skin of the Meretrix meretrix shellfish that had it
because it had died the other day, it took in the photograph.

The skin in front of of the Meretrix meretrix has flaked off.

What taken from Meretrix meretrix's inside
When the edge of the shell is seen, it is understood that the skin
has rolled the shell.