Snails are mollusks with coiled shells belonging to class Gastroda. Gastropods lacking shells are called slugs which are included (in scatters) in groups that mainly consist of snails. Snails are usually found in marine, freshwater, and terrestrial environments. Terrestrial snails are the snails that we are familiar with although a greater part of snails are not terrestrial. The snail group Pulomonata includes snails possessing lungs while snails that have gills are classified under the paraphyletic group. Most snails are herbivores but some snails (marine and land species) tend to be carnivores or omnivores in nature.

Interesting facts about nails

Many land snails can lift ten times their own weight up a vertical surface. A snail is able to sleep for as long as three years.