The mystery snail is a type of snail that lives in fresh water, as opposed to the more common land snails. Its eyes -- located at the ends of stalks that protrude from the head -- are complex body parts that mystery snails can regenerate. If the eyestalk is somehow severed mid-length, the snail can actually grow a new portion of it, complete with a brand-new eye. It takes approximately 14 days for a mystery snail to regenerate its eyestalk and about 25 days for the eye to regenerate and be outwardly visible. Eyes that are regrown after amputation tend to be smaller than the originals.
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