The critically endangered axolotl—also known as the Mexican salamander—shares a type of cell, called a glial cell, with humans. If an axolotl hurts its spinal cord, its glial cells go to work ...

Why it matters: Also called the axolote or ajolote, the amphibian was considered a god by the Aztecs and has long fascinated scientists in part because it is capable of regrowing limbs.