Biologic evolution

It is a shell found in Tokyo Bay.
The name is not written because it applies variously when the picture
book is seen though it is shellfish's name.
Please comment to understanding.

When you see the surface of the shell
It is understood that the skin with which the shell was covered peels off.
Discovering the skin
It is only a shell to have always died.
It is thought might be integral with the mechanism that the skin of the thing and the shell
to be alive cannot be found.
Said thing and some relations are mysterious ..whether.. when understanding because it has
died.