Stromatoporoids are among the most important fossil sponges because of their large encrusting or massive calcareous skeletons and extensive geologic record. On close examination of a broken surface, fine laminae can be seen running parallel to the colony surface. In some forms, pillars may cross the laminae at right angles forming a grid-like pattern. On the external surface, small bumps called monticules may be seen. Small clusters of small channels called astrorhizae diverge from the monticules.



Stromatoporoids range from the Cambrian to the Cenozoic but flourished in the Silurian and Devonian, particularly in reef environments.

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Last updated on February 24, 1997-jlc.