Cambrian – Cretaceous
Stromatoporoidea is an extinct class of stationary epifaunal suspension feeders which have been interpreted to have hosted symbiotic algae in their tissues
Characteristics of the Class
- Skeleton most often appears distinctly layered
- Surface of the colony is commonly marked by bumps
- Generally there is a hole in the center of each bump
- Pattern of shallow grooves radiating from each canal opening
- The name stromatoporoid means “layered place”. This name is appropriate because the skeleton of these colonial creatures most often appears distinctly layered, especially in thin-section. The surface of the colony commonly is marked by bumps(see, for example, Labechia on pl. VI). Generally there is a hole in the center of each bump; this is the opening of a canal feeding down into the mass of the colony. In many types of stromatoporoids there is a pattern of shallow grooves radiating from each canal opening. Stromatoporoids can be identified only after study of thin-sections of colonies.
- For many years it was thought that stromatoporoids were long extinct, and there was much question as to just what kind of creatures they were. Then in the mid-1960’s some animals were discovered in the Caribbean which exhibited many of the characteristics of the ancient stromatoporoids. These “new” animals were found to be sponges.
Nicholson & Murie (1878):
- Under Stromatopora: Skeleton (“sarcodeme”) consisting of concentric calcareous laminae, separated by distinct “interlaminar spaces”, which are crossed by numerous vertical “radial pillars”. In some cases there are radiating water-canals and surface-grooves placed round minor centres. Sometimes there are seen on the surface the openings of large water-canals (“oscula”).
- Habit- Forming irregular masses, sometimes with a foreign body as a nucleus; spreading out into extended expansions, covered inferiorly by a thin striated calcareous membrane (“epitheca”), or growing in thin layers parasitically upon foreign objects.