Middle Devonian Period coral called Romingeria umbellifera. It was found in the Jeffsonville Limestone of Clark County, Indiana.
Enhanced image from Kentucky Fossil Corals - A Monograph of the Fossil Corals of the Silurian and Devonian Rocks of Kentucky (1885) by William J. Davis, Plate 75, Figure 12. Find on-line at KPS website of Don Chesnut web adaptation.