Theriamen

A theriamen was a musical instrument resembling a floating, glowing blue cube. It could be played by caressing it, producing “eerily beautiful electronic sounds, hopeful and mournful”. Jenny Everywhere picked one up on Troynovant a long time before the collapse of the Multiverse while in the middle of an adventure, and it was one of the items that the “collapsed” Jenny retained on hand. She played a song on the theriamen to while away the time and help relieve pent-up tension in herself, Octobriana and Glendalf when the three were hiding out in a cabin in a Limbo realm. (PROSE: The Hermetic Garbage of Jenny Everywhere)

Behind the scenes

The name of the theriamen, as well as the description of its sound, point to it being an other-dimensional counterpart to a theremin, though with several significant differences.