[img width=372 height=480]http://i94.photobucket.com/albums/l110/olram9/Nerites/IMG_2735C.jpg[/img]
On jetty rocks, St. Lucie Inlet, Florida.
They look like Nerita peloronta Marlo.
Two are, plus one N. versicolor and two N. tessellata. Surprized no one noticed.