Hexagonaria is a genus of colonial rugose coral.

Fossils are found in rock formations dating to the Devonian period, about 350 million years ago.

Specimens of Hexagonaria can be found in most of the rock formations of the Traverse Group in Michigan.

[3] Based on Erwin C. Stumm [de]'s Corals of the Traverse Group of Michigan Part 13, Hexagonaria, published in 1970.

Other features diagnose the differences between species; the metrics below merely represent handy features for diagnosis in the Michigan Basin, not comprehensive diagnoses.