The Great Stalacpipe Organ is “a unique instrument that uses cave formations to make music. Conceived and built in the 1950s by mathematician Leland Sprinkle, the organ produces tones using rubber-tipped mallets to strike stalactites as its keys are played. It took Sprinkle three years and 2500 tries to find the right 37 formations to serve as natural chimes, ranging over five octaves.”