A piano, where each block indicates a different note. By clicking on the blocks while using the harp, it is possible to play a song.
The Harp is a Hardmode crafting material, used only to craft the Magical Harp. While the Harp can be used itself, it has no functional use, and only makes sounds. It is sold by the Wizard for 1 GC each.
When used, the Harp generates harp sounds. The sound's pitch is determined by the distance between the center of the character and the point clicked. Clicking the center of the character plays middle C, while clicking at a distance of at least that of the top or bottom of the screen plays C6 (two octaves above middle C). The smallest interval between notes the harp can play is a whole tone, or two semitones. A difference of 1/24 of the screen height equals an interval of a whole tone.
The Harp and the Whoopie Cushion have similar effects, although the Whoopie Cushion cannot change pitch.