Florida is covered with "Shell Mounds" (indian garbage dumps, not "Burial Mounds"). Shellfish was a staple food of indians living near waterways. You can find them everywhere (except where early settlers excavated them for roadbed and foundation materials!)...
My bad! Later "settlers" did far more shell mound destruction until the state started protecting the ones that they identified/ Obviously this is the case since bulldozers and draglines move shell far more efficiently!