Class Hexactinellida (Glass Sponges)
These are deep-sea sponges. They lack an epidermal covering, and their skeletons are composed of spicules of silica. The spicules, which often form a latticework, have six points or some multiple thereof. Glass sponges are pale in color and are cup- or basket-shaped. The spongocoel is large, and the osculum is covered by a grillwork of fused spicules. When the living tissue is removed, the cylindrical skeletons often have the appearance of spun glass. The glass sponge known as Venus's-flower-basket ( Euplectella ) supplies a home for certain shrimps that become trapped by the lattice of spicules. The body plan of Hexactinellida is between syconoid and leuconoid.
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