Colonies of I. hippuris are branched in an irregular lateral fan-like manner.  Colonies may be sparingly or densely branched. Typically the branches are short, but some colonies have long whip-like branches • Colonies of I. hippuris are characterized, as are all species of Isididae, by a skeleton consisting of calcareous internodes (composed of calcium carbonate) interspersed with nodes of proteinaceous gorgonin.  The nodes of I. hippuris are much thinner than the internodes. As a result, the internodes tend to appear “bulging” compared to the nodes , and may be globular or barrel-shaped
The surface of the calcareous internodes of I. hippuris exhibits conspicuous parallel longitudinal ridges approximately 1 mm apart. Once the coral is polished, these ridges are typically still evident as longitudinal lines in the material  In cross-section under low magnification, these will appear as weak radial lines that cross many concentric lines. These lines are particularly visible in dyed specimens
The natural colour of the calcareous internodes is white while the gorgonian nodes are dark brownblack