Florida agatized coral: photo by Fossil-Treasures-of-Florida (all rights reserved; used by permission).
Official State Stone of Florida
Florida designated agatized coral as the official state stone in 1976 (agatized coral is actually a fossil). Fossilized coral is also a state symbol of Michigan (petoskey stone). All State Stones - All State Fossils
Agatized coral can be found in three main locations in Florida: Tampa Bay, the Econfina river, and the Withlacoochee / Suwannee river beds.