A music box is a automatic, often wind-up musical instrument that produces tones by a set of pins placed on a slowly turning disc or cylinder so as to strike the teeth of a steel comb.
They were developed from 18th century musical snuff boxes and used to be called: carillons à musique.
Some of the more complex boxes also have a tiny drum and small bells, in addition to the metal tuned comb. Alec Templeton, a Welsh composer, pianist and collector of musical boxes, once said that tones of a musical box is unlike that of any other instrument. He said it is best described as somewhere between the character of a mbira.
What's it worth? Take a look at this Music Box price guide: sold listings for a value indication.