The waterphone is a real acoustic instrument made from a metal resonator with rods of different lengths, played by bowing or striking while water inside shifts the pitch and creates its wavering, otherworldly tone. Film and television sound designers have long used it to suggest dread, mystery and the supernatural without words, because its sound feels both musical and unnatural. Online, short waterphone clips have become a handy shorthand for suspense in edits, reaction videos and horror-themed shorts, where a few seconds are enough to tell viewers that something strange is coming.