Paludinella littorina, common name the lagoon snail, is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of minute half-way land and half-way sea snail

Snail

Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...

 with an operculum

Operculum (gastropod)

The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...

, a mostly terrestrial

Terrestrial animal

Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...

 but partly marine gastropod mollusk or micromollusk

Micromollusk

A micromollusk is a descriptive term for a shelled mollusk which is extremely small, even at full adult size. The word is usually, but not exclusively, applied to marine mollusks, although in addition, numerous species of land snails and freshwater mollusks also reach adult size at very small...

, in the family Assimineidae

Assimineidae

Assimineidae is a family of minute snails with an operculum that live in saltwater, freshwater or on the land; they are mostly aquatic gastropod mollusks or micromollusks, in the clade Littorinimorpha.- Ecology :...

.

Habitat

This species lives around the high tide mark in estuaries and other sheltered places on the coast, under stones and in cracks in rocks, and similar habitats.

Distribution

This very small snail occurs on the coasts of the western Mediterranean and the Atlantic north to the English Channel

English Channel

The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...

, in islands and countries including:

• Great Britain. This species is fully protected in the United Kingdom under the Wildlife and Countryside Act 1981
  Wildlife and Countryside Act 1981
  The Wildlife and Countryside Act 1981 is an Act of Parliament in the United Kingdom and was implemented to comply with the Directive 2009/147/EC on the conservation of wild birds...
  
  since 1992.