Scientists are on the trail of a mysterious five-particle structure that could challenge one of the biggest theories in physics: string theory. This rare particle—never seen before and predicted not to exist within string theory—might leave behind vanishing tracks in the Large Hadron Collider, like ghostly footprints that suddenly disappear. Spotting it wouldn’t just shake up physics theory—it might also reveal clues to dark matter, the invisible stuff that makes up most of the universe.