conchiglia

Conchiglia is the Italian term for the hard, protective shell produced by many mollusks, most notably snails (gastropods) and clams, oysters, and other bivalves. The word denotes the shell itself and is also used in a broader sense for the animals that bear shells. In Italian, conchiglia is singular and conchiglie is the plural; the term is also used for the pasta shape conchiglia, which resembles a shell.

Shells are secreted by the mantle and consist largely of calcium carbonate organized in different crystalline forms, such as aragonite and calcite, often within an organic matrix called conchiolin. They typically display layered structures, including an outer periostracum, a prismatic layer, and, in some species, a nacreous inner layer. Growth occurs at the shell margin as the animal enlarges, leading to changes in size, curvature, and ornamentation over time.

Mollusk shells serve primarily as protection against predators, environmental fluctuations, and desiccation. They are found in a wide range of environments, from marine to freshwater and, in some lineages, terrestrial settings. When empty, shells may be reused by other organisms such as hermit crabs, which select abandoned shells as portable refuges.

Human use of conchiglie and shells is diverse. Shells have long been collected for decoration, jewelry, and ornament, and large conch shells have been used as musical instruments in various cultures. The term conchiglia also appears in culinary contexts as the shape of pasta, known for its hollow, curved form. Conservation concerns include habitat loss and overharvesting, which can impact mollusk populations and the availability of shells.