Two pictures of the same fossil that is some type of Aulocystis coral found in Clark County, Indiana. It is from the Devonian Period and I believe I was in the Beechwood Limestone when I found it. This fossil is relatively small and could fit in a 2 cm cube.
This particular fossil might be a Aulocystis frutectosa described by W.J. Davis in 1887 (Kentucky fossil corals, a monograph of the fossil corals of the Silurian and Devonian rocks of Kentucky, Part 2).