Fossilized Coral Cabochon is commonly referred to as "horn coral", most likely Genus Breviphrentis.  Horn Corals are found worldwide, anywhere there were shallow seas. In North America, these corals are prevalent in Pennsylvanian and Mississippian deposits along with crinoids, brachiopods, and bryozoans and in a few places in Utah, the coral structure is bright red, although this is from the later Silurian era.

Measures 22 mm x 18 mm x 10 mm.  Approximately 7/8" x 3/4" x 3/8" 

$7