Learn which animal can sleep for three years.
It has been said that a slimy snail can sleep for three years.
It also has been said that the same slimy snail can sleep for six years.
Obviously, that kind of powerful sleeping would be better described as hibernation, or hibernation's summertime counterpart, estivation.
But whatever you call it, the snail as a species clearly has a gift for suspended animation.
Some anecdotal examples of snail hibernation were collected more than a hundred years ago in "The Cambridge Natural History" of 1895, an extremely learned (though no less outdated for it) multi-volume compendium of information on the natural world.
In particular, the authors recall the tale of one Mr. Vernedi, who found himself in Egypt in the year 1854. At a way-station in the desert, Vernedi discovered a heap of thorn bushes "rather thickly studded with snails."
For whatever inscrutable reason, Vernedi's response to this scene was to approach the bushes and pick off a large number of snail specimens, which he then took home and locked in a drawer. There they remained, untouched, in a desk drawer, in suspended animation for more than four years, before two of them were sent to the British Museum and presumably revived.
Meanwhile, here in the 21st century, science has largely abandoned the snail-in-a-drawer model of research, though we may never have a better idea of just how long a snail can sleep.