Fossilized coral is the preserved remains of ancient coral reefs that have turned into rock over millions of years. These corals, once living organisms, are primarily composed of calcium carbonate, which helps them form hard structures. When corals die, their skeletons can accumulate and eventually become buried by sediment, leading to fossilization. The process of fossilization involves mineralization, where minerals replace the organic material in the coral. Fossilized coral can be found in various colors and patterns, making it popular in jewelry and decorative items. It provides valuable insights into ancient marine ecosystems and the history of our planet's oceans.