However, the common name snail is also used for most of the members of the molluscan class Gastropoda that have a coiled shell that is large enough for the animal to retract completely into.

Snails have considerable human relevance, including as food items, as pests, and as vectors of disease, and their shells are used as decorative objects and are incorporated into jewellery.

Snails can be found in a very wide range of environments, including ditches, deserts, and the abyssal depths of the sea.

Most snails have thousands of microscopic tooth-like structures located on a banded ribbon-like tongue called a radula.

[3] Several species of the genus Achatina and related genera are known as giant African land snails; some grow to 38 cm (15 in) from snout to tail, and weigh 1 kg (2 lb).

Named Gee Geronimo, this snail was owned by Christopher Hudson (1955–79) of Hove, East Sussex, UK, and was collected in Sierra Leone in June 1976.

Both land and sea snails travel by contracting foot muscles to deform the mucus layer beneath it into different wave-like patterns.

The inner layers of the shell are composed of a network of calcium carbonate, conchin, and different mineral salts.

The mantle produces the shell through addition around a central axis called the columella, causing a spiraling pattern.

In larger populations, adult snails attain smaller shell sizes due to the effects of pheromones on growth rate.

Snails can be herbivores, detritivores, scavengers, parasites, ciliary feeders, or have highly specialized predation.

The teeth and membrane are continuously synthesized in the radular sac and then shifted forward towards the working zone of the radula.

The presence of the radula is common throughout most snail species, but often differs in many characteristics, like the shape, size, and number of odontoblasts that form a tooth.

The average snail's diet varies greatly depending on the species, including different feeding styles from herbivores to highly specialized feeders and parasites.

For example, Cepaea nemoralis, or the grove snail, prefers dead plant material over fresh herbs or grasses.

Slugs squeeze themselves into confined spaces such as under loose bark on trees or under stone slabs, logs or wooden boards lying on the ground.

[21] Snails can also be associated with parasitic diseases such as schistosomiasis, angiostrongyliasis, fasciolopsiasis, opisthorchiasis, fascioliasis, paragonimiasis and clonorchiasis, which can be transmitted to humans.

Land snails are known as an agricultural and garden pest but some species are an edible delicacy and occasionally household pets.

A layer of a dry, finely ground, and scratchy substance such as diatomaceous earth can also deter snails.

However, this is not without problems, as the decollate snail is just as likely to attack and devour other gastropods that may represent a valuable part of the native fauna of the region.

As well as being eaten as gourmet food, several species of land snails provide an easily harvested source of protein to many people in poor communities around the world.

Many land snails are valuable because they can feed on a wide range of agricultural wastes, such as shed leaves in banana plantations.

[29] In Bulgaria, snails are traditionally cooked in an oven with rice or fried in a pan with vegetable oil and red paprika powder.

[citation needed] Snails and slug species that are not normally eaten in certain areas have occasionally been used as famine food in historical times.

A history of Scotland written in the 1800s recounts a description of various snails and their use as food items in times of plague.