The sponge is an aquatic animal. It clings to a hard object such as rock or coral. Through a system of chambers it ingests the plankton on which it lives.

Every two months the growing sponge increases in diameter by half an inch. The sponge is coated with a dark elastic skin. The skin has openings through which the sponge breathes. Gurry, a gray, gelatin-ous substance, is found between the outer and inner skins of the living sponge.

Divers gently squeeze out the gurry as they gather their sponges. Then they pound them down and clean them. The sponges are covered with wet burlap sacks on the ship’s deck. The heat releases a gas that rots the sponges’ skins. The natural sponges we use are actually the skeletons of aquatic animals.