The hydra is named after the serpent monster from Greek myth, which regrows two heads each time one is cut off. But freshwater hydras have an even more impressive regenerating ability: an entire hydra can regrow from a small piece of tissue in only a few days.

Biologists are particularly excited by this ability, since many of the networks involved in the healing process developed early in the process of evolution, meaning that they are shared among many animals, including humans.

“In other organisms, like humans, once our brain is injured, we have difficulty recovering because the brain lacks the kind of regenerative abilities we see in hydra,” said researcher Abby Primack.