Renaissance notation knives

Renaissance notation knives had music inscribed on the blades. Each blade had the music for one voice as part of a chorus who would sing the benediction or grace at a meal. If you listen to the video at the end of the article, you will hear some lovely music.
http://www.openculture.com/2017/07/renaissance-knives-had-music-engraved-on-the-blades-now-hear-the-music-performed-by-modern-singers.html