Biologic evolution

It is quite difficult to observe the life of the seawater thing in
the sea.
The action of the living thing in the sea cannot be completely
understood and the way.
Information obtained by keeping the living thing in the sea with the
water tank is a little.
Therefore,
There are a lot of things that do not understand.
The photograph is hardening of the sand of the sea.
On earth..which..shellfish..such..dexterous..sand..harden..think.
It had published before.
The photograph where Tsmeta shellfish's sand had been hardened was
published.
I am surprised to see shellfish's mysterious ability.

How is sand hardened?
The liquid to which sand is hardened?Is it a null?
It is thought that enlarging the shell uses the sand of the sea.
How is the sand of the sea made a shell?
It is mysterious.