Here is a Devonian coral called Aulacophyllum . It was found in central Jefferson County, Kentucky. It looks pretty worn and is about 6 cm...

Cystiphyllum horn coral from the Silurian Period. It was found in central Jefferson County, Kentucky in the Louisville Limestone. One key...

Here is a Mississippian horn coral found in Crawford County, Indiana. It is small maybe 3 cm in height.