Stromatoporoidea


Stromatoporoidea is an extinct clade of sea sponges common in the fossil record from the Ordovician through the Devonian. They were especially abundant in the Silurian and Devonian. These invertebrates were important reef-formers throughout the Paleozoic and the Late Mesozoic. The group was previously thought to be related to the corals and placed in the Phylum Cnidaria. They are now classified in the phylum Porifera, specifically the sclerosponges. There are numerous fossil forms with spherical, branching or encrusting skeletons of laminated calcite with vertical pillars between the laminae. Specimen of its oldest genus, Priscastroma, have been found within the Middle Ordovician Sediments. This same genus has been referred to as the species P. gemina Khrom., and is known to have been known to branch off into two forms, A and B. Form A gave rise to the genus Cystostroma while form B gave rise to the genus Labechia and its descendants.
Stromatoporoids are useful markers whose form and occurrence can diagnose the depositional environment of sedimentary strata.
Paleozoic stromatoporoids hosted various symbiotic endobionts such as rugosans, syringoporids, worms and cornulitids.