Harpsichord
The harpsichord was an ancient musical instrument from the planet Earth, similar to a piano.

Trelane had an old harpsichord in his mansion on Gothos. As the  away team entered his mansion in 2267, he was seated at the instrument, playing.

Later, he wanted to dance with Teresa Ross and asked Nyota Uhura to accompany them on the harpsichord. When she protested that she didn't know how to play, he gave her the ability to do so. ()

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Earth musical instruments