These were abundant on the trunks of red mangroves and other logs and trees at low tide at J.R. Ding Darling NWR. The set here was photographed along the Calusa Shell Mound Trail where I could lean in and get close enough for photography.

The spire on the first shell looks a bit taller than the others and I'm wondering if Eastern Melampus (M. bidentatus) might occur with these Coffee Melampus in the same habitat.