Axolotl

01Tilikum was responsible for three human deaths: Keltie Byrne (1991), Daniel Dukes (1999), and Dawn Brancheau (2010).
02Despite the deaths, SeaWorld continued using Tilikum for breeding; he sired 21 calves, propagating his genes through the captive population.
03He was captured at age two, separated from his mother, and held in a concrete pool — trainers noted severe psychological deterioration over decades.

Piles of new Notgeld banknotes awaiting distribution at the Reichsbank during the hyperinflation

The axolotl never undergoes metamorphosis — it breeds, ages, and dies as a permanent larva — and can regenerate a functional heart, spinal cord, and portions of brain within weeks.