Lophophyllidium spinosum

Lophophyllidium spinosum is a fairly common and easily recognizable rugose coral due to its many protrusions; another common species, L. plummeri, doesn't have this feature. Rugose corals can either be solitary (like those pictured here), or colonial, like the well-known Hexagonaria that most people recognize as Petoskey stone. Solitary corals are often called "horn coral" due to their shape and, although rugose corals died out during the Permian mass extinction, other solitary corals can be found in the Cretaceous (like Parasimilia) and the Eocene (like Turbinolia).

For further reading on rugose corals, I suggest the page "Rugose Coral" from Digital Atlas of Ancient Life and "Interesting Horn Corals" from Fossil Lady.

Genus/Species: Lyphophyllidium spinosum
Locality: Finis Shale member of the Graham Formation
Age: Late Carboniferous (Pennsylvanian)
Dimensions: varies
Self-collected many specimens between 2019-2022.