A land snail is a common name for any of the numerous species of snail that live on land, as opposed to those that live in salt water and fresh water. Land snails are terrestrial gastropod mollusks that have shells (those without shells are known as slugs). In reality however, it is not always easy to say which species are terrestrial, because some are more or less amphibious between land and freshwater, and others are relatively amphibious between land and saltwater.