A fine Middle Devonian fossil specimen of a Heliophyllum infundibulum horn coral hosting another coral colony of Aulocystis transitorius. I found this coral in the Beechwood Member, North Vernon Limestone, Givetian Stage of Clark County, Indiana, USA and my cousin Kenny cleaned it with air abrasion. It looks so much different when I spotted it. One could tell it was a horn coral and had another coral colony but WOW he really uncovered a nice size colony on this specimen.
Thanks to Kenny for the pictures.