ShellSanibel
Read the beach.
Florida cerith
Cerithium atratum
common · 0.5–1.5 in (1–4 cm)
How to tell it
A small, sharply pointed spire with beaded spiral rows. Grey-brown, often with paler flecks.
What it gets confused with
Several small ceriths and horn shells are near-identical without a lens. This is a genus you can be confident of and a species you should be humble about.
Where it turns up
Everywhere small material collects — the fine wash, the base of the wrack line.
Alive or empty
Grazes algae in shallow water; live ones are abundant on the flats.
Taking live shells is prohibited in Lee County
That includes anything with the animal still in it, and sand dollars, sea stars and urchins whether or not they look alive. If it moves, if it closes, if it is anchored to the sand — put it back where you found it, the right way up.
A shell with an animal in it is not a souvenir that has been left out. It is the animal’s house, and the beach is not producing spares.