Blothrophyllum coral from the Centerfield formation
Identifying Rugose, or horn, corals takes some effort and sometimes not all the details you need are present. Most of the horn corals that I find are generally either Heliophyllum or Cystiphylloides Occasionally I find some different genera like the two specimens below which are Blothrophyllum sp. from the Centerfield mbr. of the Ludlowville formation in central New York. The give away is the way the corallite structure grew. If you examine the side of the corallite they are not smooth like Heliophyllum or Cystiphylloides. Instead they rough and sculpted and sometimes look like a cone in cone type structure.