Silurian Coral Reefs
The Silurian was a time of extensive reef development within the shallow and tropical Paleozoic seas. The major reef-forming animals were tabulate corals, rugose corals and stromatoporoids, an extinct type of sponge.
Corals are made up of small invertebrate animals like tiny sea anemones. They feed on small food particles found in the water around them while depositing a hard exoskeleton made of calcium carbonate which is usually fossilized. Together they form colonies and many colonies form reefs.
Rugose Corals
In rugosan colonies, each corallite skeleton had its own chamber wall while horizontal partitions (tabulae) were absent and septae longer and generally more complex than those in tabulate corals. Although most rugose corals were solitary animals shaped like a horn (horn corals), some grew in groups such that their skeletons were touching and formed mound-shaped colonies.
Tabulate Corals
The Tabulata are an extinct form of coral. Their distinguishing feature is their well-developed horizontal internal partitions (tabulae) within each cell, but they have reduced or absent vertical internal partitions (septae) . They share the cell walls. The entire tabulate coral is called the corallum, while the individual tubular chambers within the corallum, in which the coral animal (polyp) lived, are called corallites. Most tabulates were colonial and they were the principal Silurian reef former.
Favosites
A genus of extinct corals having polygonal cells with perforated walls commonly forming colonial mounds resembling honeycombs or wasp nests.
Heliolites
Tabulate corals in which calcareous tissue was shared among cojoined corallites in highly interconnected colonies.
Halysites
Halysites are tabulate corals called "chain coral" because their cell walls were attached to one another side-by-side in wavy lines resembling a chain.
