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Hydnoceras

Hydnoceras The thin walled, vase shaped, Hydnoceras nis a fine example of a glass sponge, with an open structure of spicules forming a rectangular meshwork. Bulbous swellings appear along the longitudinal ridges. Habitat -- Living glass sponges are found only in deep water, but they were once common at all depths. Remark -- This fossil is cast in sandstone, preserving the filling of the skeleton but not the skeleton itself. The meshwork is clearly visible, but not the spicules themselves. Copyright © 1992 Dorling Kindersley Limited, London Text copyright © 1992 Cyril Walker, David Ward .