“Marilyn Martorano first laid eyes on the long, baguette-shaped rocks almost four decades ago, as a volunteer at what is now Great Sand Dunes National Park and Preserve in southern Colorado. The clearly hand-shaped stones, which had been discovered in the area, were housed in the on-site museum when Martorano first saw them. They were a strange set of artifacts for which no one had yet determined a use.” Thirty years later, a video someone sent her made her realize that the rocks made up a percussion instrument now called a lithophone.