ShellSanibel
Read the beach.
Coquina
Donax variabilis
abundant · 0.3–1 in (1–2.5 cm)
How to tell it
Tiny wedge-shaped bivalves in every colour combination the Gulf can manage — pink, yellow, blue-grey, striped, rayed. No two alike, which is the point of the name variabilis.
What it gets confused with
Nothing else this small is this colourful in this shape.
Where it turns up
The swash zone itself. Watch the sand after a wave retreats and you will see them burrowing back down.
Alive or empty
Overwhelmingly alive. A pair of matched halves still hinged and closed is a living animal, not a find. Leave them; they are the base of the beach food web here.
Worth knowing
The single most common thing underfoot, and the one most often taken by mistake.
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.