Limacina helicina is a species of small swimming planktonic sea snail in the family Limacinidae, which belong to the group commonly known as sea butterflies (Thecosomata). Limacina helicina is a keystone species of mesozooplankton in Arctic pelagic ecosystems. The first written record of this species was by Friderich Martens from Spitsbergen in 1675. Limacina helicina was also observed during a 1773 expedition to the Arctic led by Constantine John Phipps on the ships HMS Racehorse and on HMS Carcass and the species was described one year later, in 1774.