Earthworms in Winter
During winter most worms stay in their burrows, prisoners below soil
frozen hard as rock and topped by ice and snow. They are coiled into
a slime-coated ball and go into a sleep-like state called estivation,
which is similar to hibernation for bears. (The mucous, or slime, keeps
the worms from drying out.) Worms will survive in frozen or dry soils
by estivation until conditions improve.