The rugose corals are all extinct and lived between the Cambrian and the Permian. They lack septae. Tabulate corals occur in the fossil record between the Ordovician and the Permian. Most are colonial, but a few are solitary. Many are reef-builders.
Modern corals range from the Triassic to the present.
Images of Fossil Corals . Brian Engel, University of Newcastle. This site from Australia has a great introduction to the fossil corals and an extensive gallery of photographs of sections through fossils of many different coral types. Introduction to the Cnidaria . University of California at Berkeley Museum of Paleontology.