Trelane's harpsichord
The harpsichord is an ancient piano-like musical instrument from planet Earth.
Trelane had an old harpsichord in his mansion on Gothos.
When he wanted to dance, he made Uhura play the instrument. She didn't know how to do that, but with a wave of his hand, Trelane taught her how to play. (TOS: "The Squire of Gothos")