The Mark Pardo Shellworks Site on the eastern edge of Cayo Costa Island in Cayo Costa State Park preserves evidence of long Indigenous occupation along Florida’s Gulf shore. Its shoreline shell works and inland black dirt middens contain mostly lightning whelk, along with horse conch, oyster, clam, and other shells. Archaeologists have suggested related remains may also survive underwater in the adjacent black mangrove forest from a time of lower sea level. Attributed to the Caloosahatchee culture during the IIA-IV period, about 500 to 1500, the site was regarded as one of the region’s best preserved archaeological places, despite serious later damage from feral hogs.