These small guitar-like/ukelele like instruments can play elaborate melodies, and are native to Bolivia and the Andes area. And the back of the instrument used to be made from the back of an armadillo! Today they are mostly made all from wood, but the back is in a bowl shape. There are 10 strings, like a 10 string guitar . . . but they are fitted on a very small fretboard, as this instrument is about the size of a ukelele.
The charango is thought to be a native Andean invention based on ancestors of the classical guitar that were brought to the Andes by the Spaniards. Strings can be either metal or nylon. The tone range is fairly high-pitched, with multiple strings playing together, and I think it sounds beautiful.
Here is a well-known charango player, Ernesto Cavour from Bolivia, playing a piece called Leno Verde (Green Log).