Snails can sleep for 3 years.

We're lucky to even see them move! The reason snails sleep is they alike many other animals hibernate. Hibernation means that they sleep when weather becomes excessively cold, this is a necessity in survival. Snails will bury themselves in the ground and close their shells off with their own slime. It is also been known some species of desert snails can do this for years before actually dying. http://www.associatedcontent.com/