Agatized Coral formations began as living coal reef 400 million years ago, in the shallow seas over Florida. They are found in ancient ocean beds, where silica rich groundwater has percolated through them and over time has replaced it's calcium carbonate skeleton with a hard variety of Chalcedony. This leaves the ornamental fossil with a sometimes banded stone look. From the Oligocene-Miocene period, these fossils are found in a variety of colors- white, gray, brown, black, yellow and red. Different trace minerals in the agate create these colors. Now named the state stone of Florida, these excellent prehistoric fossils are sought after by collectors of all types.