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 Ordovician to Silurian (from 449.5 to 412.3 Ma). Fossils of Halysites species have been found in the sediments of Canada, United States, Poland and Australia.