They were a type of coral, called rugose corals, that flourished in the mid- to Late Paleozoic but went extinct at the end of the Paleozoic. You found the coral in an area that is underlain by the Tanglewood Limestone Member of the Lexington Limestone. It is Middle Ordovician in age (471.3-458.2 million years ago). The hexagonal chambers are where the individual coral polyps would have lived in the colony. You can see that they are stacked in columns that were formed as the colony grew in size and numbers of individual polyps. The specimen, found in Lexington, KY, has been weathered and spent time within the soil, collecting red residual clay and other minerals as the host limestone bedrock dissolved.

Approximately 8"