Biologic evolution

Corbicula's skin took a picture of the one that had been cut down by the
external cause.
As for the photograph of the shellfish from which the skin peels off, there
are a lot of taking a picture of the dying shellfish usually.
The reason for the shellfish from which it dies and time has passed is that
it is the one that nature and the skin peel off.
The corbicula in the photograph of today is alive.

I think that the reason why the apex of shell whitens is peeling off of the
skin as shown in the photograph of today.