The Queen Conch (Aliger gigas), also commonly known as the pink conch, is a species of large edible sea snail, a marine gastropod mollusk in the family of true conches, the Strombidae. This species is one of the largest molluscs native to the Caribbean Sea, and tropical northwestern Atlantic, from Bermuda to Brazil, reaching up to 35.2 centimeters (13.9 in) in shell length. The queen conch is closely related to the goliath conch (Lobatus goliath), a species endemic to Brazil, as well as the rooster conch (Lobatus gallus).
The queen conch is herbivorous. It feeds by browsing for plant and algal material growing in the seagrass beds, and scavenging for decaying plant matter. These large sea snails typically reside in seagrass beds, which are sandy plains covered in swaying sea grass and associated with coral reefs, although the exact habitat of this species varies according to developmental age. The adult animal has a very large, solid and heavy shell, with knob-like spines on the shoulder, a flared, thick outer lip, and a characteristic pink or orange aperture (opening). The outside of the queen conch is sandy colored, helping them blend in with their surroundings. The flared lip is absent in juveniles; it develops once the snail reaches reproductive age. The thicker the shell's flared lip is, the older the conch is. The external anatomy of the soft parts of the queen conch is similar to that of other snails in the family Strombidae; it has a long snout, 2 eyestalks with well-developed eyes, additional sensory tentacles, a strong foot and a corneous, sickle-shaped operculum.
The shell and soft parts of living queen conches serve as a home to several different kinds of commensal animals, including slipper snails, porcelain crabs and a specialized species of cardinalfish known as the conchfish (Astrapogon stellatus). Its parasites include coccidians. The queen conch's natural predators include several species of large predatory sea snails, octopus, starfish, crustaceans and vertebrates (fish, sea turtles, nurse sharks). It is an especially important food source for large predators like sea turtles and nurse sharks. Human capture and consumption dates back into prehistory.
Its shell is sold as a souvenir and used as a decorative object. Historically, Native Americans and indigenous Caribbean peoples used parts of the shell to create various tools.
International trade in the Caribbean queen conch is regulated under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) agreement, in which it is listed as Strombus gigas. This species is not endangered in the Caribbean as a whole, but is commercially threatened in numerous areas, largely due to extreme overfishing.