Trudging along to a slow, mournful song, more than a thousand dancers in elaborate costumes fill the streets for the Bolivian Carnival of Oruro. As the procession advances, the dancers twist the wooden handles on their matracas, or rattles, which make a hollow, clattering sound.

Look closer, and you’ll see that the matracas have faces. They’re pointy and belong to an animal that resembles a furry coconut: the Andean hairy armadillo. The creatures are one of the star attractions of the carnival in Oruro, a city in western Bolivia, which takes place every year around Mardi Gras. Their shells are embroidered on costumes, hollowed out and made into rattles, or used as the body of guitars. (When Bolivians hunt the armadillos for use as carnival…