Armadillos are among the most curious-looking creatures in the animal kingdom. Beyond appearance, they also have another unusual characteristic: they always give birth to identical quadruplets.

The nine-banded armadillo (Dasypus novemcinctus) female only produces a single egg. That egg splits into four seperate parts after fertilization. This produces four identical offspring.

Scientists speculate that the adaptive benefit may be that since all of the quadruplets are the same sex, there is no danger of inbreeding between the litter mates. Unlike other animals, armadillos do not have a defined territory. When they mature, rather than being driven off, they merely wander off. This could present an inbreeding problem. Since all siblings are the same sex, however, it is not an issue.

One other fun fact about armadillos: they are the only creatures aside from humans that can get leprosy.

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