Biologic evolution

It took a picture of "Null" of Nishisazae.

Fta of the shell went out and "Null" had gone out from among a half opening.

The water tank doesn't put air.

It was understood that "Null" expanded toward the surface of the water because
there was no flow of seawater.

The shellfish might put out how of "Null" to put it out by thinking about the direction of seawater and the position of the shell feeling the flow of seawater.

With the shellfish according to the living thing of water (Obunsha Co Ltd BOOK)

The element of the shell seems to be "Calcium carbonate. "