Beautiful alive Limpet. Limpets are cone-shaped shells that look like tiny volcanoes. They cling tightly to rocks, seawalls, and mangrove roots along the Gulf and Atlantic coasts. Low cone or cap-shaped shell sometimes has a small hole near the top (keyhole limpet) they have ridges and usually ½ inch to 2 inches in size … they can be Tan, gray, brown, sometimes mottled. They can be found in tide pools, ricky areas, jetties, seawalls and mangroves. Limpets are found all over SWFL, Marco Island, N