Biologic evolution

Object of mystery
It be what on earth?
The answer is not understood.
However, I think that it is crow shellfish's in my little experience.
It is uncertain whether the crow shellfish is making it from what purpose.
When you say whether to have concluded crow shellfish's why
It cleaned in the water tank tank, and, perhaps, I thought that it is about five years the other day.
The shellfish included only the crow shellfish in the tank.
It thought so because it was by the crow shellfish.
There were a lot of one of the one in the tank that was the straight line.
This object similarly has the shape of one line, and the inside is a cave.
Like the straw.
In addition, hardness like shellfish.
Material feeling that can be thought like cement.
For what on earth is done will the crow shellfish do these kind of things?
The action in the sea is not straw.
I think that it can have worn this object by time's passing.
It is strength as not possible to be done at all for a day and one week.