Wikipedia
Enchytraeidae
The Enchytraeidae are a microdrile oligochaete family. They resemble small earthworms and include both terrestrial species known as potworms that live in highly organic terrestrial environments, as well as some that are marine. The peculiar genus Mesenchytraeus is known as "ice worms", as they live in glaciers and will die if exposed to temperatures a few degrees above freezing. Apart from these, the best-known species is probably the Grindal Worm (Enchytraeus buchholzi), which is commercially bred as aquarium fish food.