Hello, this item is a coral fossil, likely belonging to the genus Favites or Favia, both common colonial stony corals that thrived during the Miocene to Pleistocene epochs. The specimen shows a dense calcareous structure with visible septa and corallite chambers, typical of fossilized reef-building corals. Its grayish-white coloration with calcite replacement suggests natural mineralization over millions of years, often found in marine sedimentary formations.

Coral fossils like this are collected for educational, decorative, and geological purposes rather than rarity. Their value depends on preservation, species identification, and size. Given the well-defined cellular structure and intact surface, this specimen would fall into a mid-range collector category. Comparable examples of similar size and preservation typically sell between 40 and 80 USD.