Here is a small horn coral (1.5 cm diameter and 4.5 cm length) that is called Tabulophyllum zaphreniforme (Davis). It is found in the Beechwood Limestone layer, Givetian Stage, and was found in Louisville, Kentucky (central Jefferson County).
This horn coral was known by several other names: Amplexus yandelli Rominger 1876 and Blothrophyllum zaphrentiforme Davis 1887. E.C. Stumm describes it in Silurian and Devonian Corals of the Falls of the Ohio on page 50, "Coralla simple; subcylindrical to narrowly ceratoid with typical rejuvenation seen where epitheca has been removed. Calyx with steeply sloping walls. Septa 60-74; major extending almost to axis and probably amplexoid; minor short peripheral ridges."
See Plate 102 of the Blothrophyllum zaphrentiforme figures 8-15 in Kentucky Fossil Corals A Monograph of the Fossil Corals of the Silurian and Devonian Rocks of Kentucky by William J. Davis.
It lived in the Middle Devonian Period (397-385 million years ago) in a shallow tropical sea that covered the area of Jefferson County. Also see this image at the Indiana Memories Database.