I love finding unusual musical instruments

Especially at yard sales or flea markets. This one's a charango, with ten strings, typically used in South American music. Its paired strings are tuned GCEAE (low to high), with the middle E strings having the same note an octave apart. The back is an armadillo shell. Below is a demonstration of how one sounds.

https://www.youtube.com/watch?v=HeTHAh3nyIw