Cittarium pica

In some Spanish-speaking parts of the Caribbean, when used as a food source Cittarium pica is known as bulgao, or simply as caracoles (snails, in Spanish).

Cittarium pica is considered the third most economically important invertebrate species in the Caribbean, after the spiny lobster (Panulirus argus) and the queen conch (Eustrombus gigas).

The columella is arcuate, produced above in a heavy porcellanous callous deposit, half-surrounding the umbilicus and deeply notched in the middle.

The shell of Cittarium pica presents a rather wide umbilicus, which is deep[5] and devoid of sculpture,[7] but spirally bicostate inside.

[7] Juvenile individuals possess shells ornamented by spiral lines and strong cords, in contrast to the nearly smooth, homogeneous surface of mature specimens.

Young shells, or well-preserved adults, have the spire whorls sculptured by oblique folds, cut by a few spiral sulci.

[10] On some old, empty shells of large individuals, the black colored parts become slightly higher in relief, compared to the white areas surrounding it.

This unusual morphology may be due to the action of blue-green algae, such as Plectonema terebrans, which continuously erode the surface of the white parts of the shell.

[7] This species occurs rarely in the Florida Keys, and in the Caribbean coast of Mexico, Costa Rica, Panama, Colombia and Venezuela.

It also occurs in the Bahamas, Cuba, the Cayman Islands, Jamaica, Haiti, the Dominican Republic, Puerto Rico, and the Lesser Antilles as far south as Barbados and Trinidad and Tobago.

[2] This large snail is found on or under rocks, in exposed and moderately sheltered shores, both in intertidal and shallow subtidal zones.

[7] The sessile vermetid gastropod Dendropoma corrodens (also known as ringed wormsnail) and the tube dwelling polychaete Spirorbis may live attached to the shell of Cittarium pica, as is also the case for several species of algae.

The wide and deep umbilicus of Cittarium pica is very distinctive. This shell has been polished.
Drawing of a shell of Cittarium pica
An empty shell of Cittarium pica which has been polished to make it look more attractive
Rocky shore on St. Croix US Virgin Islands, habitat of Cittarium pica
A small shallow seawater pool found on St. Croix's north shore
The land hermit crab, Coenobita clypeatus , often uses a shell of Cittarium pica