To my amazement, there don't seem to be rocks in the northeastern part of Florida that I now reside in. The rock in this image is an aggregate of shells called coquina that is rocklike, but not a real rock in the sense I know it.
*" Also known as coquina, from the Spanish for cockleshell, Anastasia limestone is composed primarily of shell and coral fragments, fossils and sand. Small fossils are clearly visible in the rock faces, most commonly the shells of small clams and oysters or pieces of a large snail called Busycon." from the Nature Conservancy's Blowing Rocks Preserve website.