Xenophora gigantea Schepman, 1909 - great carrier snail. (apical view) (public display, Bailey-Matthews Shell Museum, Sanibel Island, Florida, USA)

This species is also known as Stellaria gigantea.

The gastropods (snails & slugs) are a group of molluscs that occupy marine, freshwater, and terrestrial environments. Most gastropods have a calcareous external shell (the snails). Some lack a shell completely, or have reduced internal shells (the slugs & sea slugs & pteropods). Most members of the Gastropoda are marine. Most marine snails are herbivores (algae grazers) or predators/carnivores.

The xenophorid snails (a.k.a. carrier snails), especially those in the genus Xenophora, are remarkable for their tendency to pick up other shells, skeletal fragments, rocks, or corals (sometimes still alive) from their surrounding environment and cement these objects to their own shells. The result looks like a pile of shells on the seafloor. Often, sponges and serpulid worm tubes are found encrusting the xenophorid shell - they contribute to the illusion that a xenophorid is simply a patch of seafloor. Xenophora carrier snails do this as a camouflage defense against predators. Decorator crabs are arthropods that engage in similar camouflage behavior (<a href="http://storage.montereybayaquarium.org/storage/animals/520x260/decorator_crab.jpg" rel="nofollow">storage.montereybayaquarium.org/storage/animals/520x260/d...</a>).

Xenophorids are principally detritivores and occur on unconsolidated, fine-grained to coarse-grained to rubbly substrates.

From museum signage: "The worldwide family of carrier-shells has for millions of years had a natural habit of attaching other shells and small objects to themselves. The family name, Xenophoridae, means "bearer" (phora) of "foreigners" (xeno). Of the 20 known living species, three live in the Caribbean Province, one in the Mediterranean, one in West Africa, and the remaining 15 in the Indo-Pacific oceans. Carrier shells will attach nearly any object within their reach. A choice of size and orientation is deliberately made. Only dead bivalves are selected and are always glued with the concave side up. Dead gastropods are always glued at the smaller, pointed end. A carrier-shell may take an hour to move an object into position with its proboscis. As many as 10 hours are taken to secrete enough new shell material to successfully "glue on" the new item."

Classification: Animalia, Mollusca, Gastropoda, Xenophoroidea, Xenophoridae

Some info. from Harasewych & Alcosser (1991) and Hill (1996).

More info. at: <a href="https://en.wikipedia.org/wiki/Xenophora" rel="nofollow">en.wikipedia.org/wiki/Xenophora</a> and