These snails, the shells of which were about 5 mm high, are littorinids family Littorinidae.    From Wordnik.com.  [Archive 2006-09-01] Reference

And then there are several semi-terrestrial groups: Littorinidae, Hydrobiidae, Potamididae, you name it.    From Wordnik.com.  [What is a terrestrial animal?] Reference

Littoraria angulifera and its relatives family Littorinidae satisfy the first 2 requirements: they can breathe air and their shells, which evolved in the oceans and were definitely a preadaptation for terrestrial life, protect them from drying when they are out of the water.    From Wordnik.com.  [Archive 2006-01-01] Reference