Here is a image of a Cystiphyllum horn coral found in north east Jefferson County, Kentucky. It is from the Middle Devonian period in the Jeffersonville or Beechwood Limestones. You can see evidence of the cysts or sacks on this coral. This coral was later renamed Cystiphylloides I believe for the Devonian Period corals and Cystiphyllum was used for Silurian Period corals.
Identification from Erwin Stumm's Silurian and Devonian Corals of the Falls of the Ohio pp. 54-55 (description) and plate 55 pp. 146-147.