1. Sea levels rose in the Devonian, and tabulate corals became much less common. 2. Rugose and tabulate corals became extinct. 3. The exposure is unique large and diverse tabulate corals and rugose corals are exposed in lifelike positions. 4. These tabulate corals lived from Ordovician to Silurian ( from 449.5 to 412.3 Ma ). 5. These tabulate corals lived from Ordovician to Devonian ( from 471.8 to 412.3 Ma ). 6. With Stromatoporoidea and rugose corals, the tabulate corals are characteristic of the shallow waters of the Silurian and Devonian. 7. These tabulate corals lived from the Ordovician to the Permian period ( from 449.5 to 279.5 Ma ). 8. Later, during the Silurian period, Missouri was home to abundant lacy bryozoans, conodonts, tabulate corals, tetracorals, abundant crinoids, trilobites. 9. The "' tabulate corals "', forming the rugose corals, but vary considerably in shape, from flat to conical to spherical. 10. Tabulate corals occur in limestones and calcareous shales of the Ordovician and Silurian periods, and often form low cushions or branching masses of calcite alongside rugose corals.