Science & TechFact
An animal that simply regrows a lost leg.
The axolotl, a Mexican salamander, regenerates entire limbs, parts of its heart and even sections of its brain, without scarring. It stays in larval form with external gills all its life yet still reaches sexual maturity. Nearly extinct in the wild, it's a standard lab animal worldwide.
Useful: Axolotl research asks why mammals largely lost this ability.
Source: en.wikipedia.org