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At the top of our immortal animals list is a tiny variety of jellyfish known as Turritopsis doohmii, or more commonly, the immortal jellyfish. It has found a way to cheat death by actually reversing its aging process, according to National Geographic. If the jellyfish is injured or sick, it returns to its polyp stage over a three-day period, transforming its cells into a younger state that will eventually grow into adulthood all over again. Here’s how to properly treat a jellyfish sting.
There is a debate among the scientific community whether these red ocean dwellers are biologically immortal animals; a common cause of death is disease, not old age, and unlike other animals, lobsters grow and reproduce until they die. One lobster captured off the coast of Newfoundland was estimated to be 140 years old, but most males survive into their early 30s while females live an average of 54 years, according to Smithsonian. Fun fact: The bigger the lobster, the older it is.