The halysitids are a group of extinct, Paleozoic-aged colonial corals. They are readily identifiable - their corallites are linked end-to-end in a distinctive pattern resembling chains (hence the common name “chain corals”). Halysitids are one of the several families of Paleozoic tabulate corals. They were an important reef-building component in the Silurian throughout the world. They occur in shallow-water marine carbonate facies.
Classification: Animalia, Cnidaria, Anthozoa, Tabulata, Halysitidae
Halysites louisvillensis (apparent junior synonym of Halysites nitidus) from the Louisville Limestone (upper Middle Silurian to lower Upper Silurian) of Jefferson County, Kentucky, USA. This colony has been silicified - the original skeleton was composed of calcium carbonate (CaCO3). Falls of the Ohio State Park collection, Clarksville, Indiana, USA.