Halysites

Halysites (meaning "chain coral") is an extinct genus of tabulate coral. Colonies range from less than one to tens of centimeters in diameter, and they fed upon plankton.
These tabulate corals lived from the Ordovician to the Devonian (from 449.5 to 412.3 Ma). Fossils of "Halysites" species have been found in the sediments of North America, Europe, Asia and Australia.
Species.
Species in the genus "Halysites" include: