This is such a unique instrument! This “viola organista” was designed by DaVinci, who never was able to see his creation built, as far as we know. Essentially, it has strings like a piano but instead of hammers to hit the strings there are wheels with horsehair (like a bow) that rotate when powered by a foot pedal. When the player presses a key the string is pushed down until it connects with the spinning wheel which then causes the sound. So neat! Check out the full article here.