Found in South America, the southern three-banded armadillo "are the only species of armadillos capable of rolling into a complete ball to defend themselves."
From Wikipedia:
The three characteristic bands that cover the back of the animal allow it enough flexibility to fit its tail and head together, allowing it to protect its underbelly, limbs, eyes, nose and ears from predators. The shell covering its body is armored and the outer layer is made out of keratin, the same protein that builds human fingernails.
