As additional shell material is laid down, the animal becomes heavy, sinks to the bottom, and takes up its adult existence.

This mantle reacts to the sand by making layers of shell material around it.

The outer shell material also was changed to a sage green cotton-nylon blend, with respective percentages 80-20, 65-35, and 50-50 being used at various times.

They became purplish-brown at the margins where new shell material was laid down.

Additional shell material is laid down by the mantle tissue to compensate for this.

No trace of the original shell material remains.

As the animal gradually matures, the mantle continues to secrete shell material.

Linings Most lightweight sleeping bags are made of the same shell material inside and out.

Irravel studied a Slug now, crawling out from under a lip of shell material.

The callum is an area of shell material that fills the gap between the two valves.