On Wednesday, 13 December, CERN invites you to "Embark on the search for the invisible." Particle physicists are almost like detectives relying on their powers of deduction to find the culprit who left weird tracks. Which particle was it? Where did it come from? If no one saw it, was it ever really there?" You are encouraged to register to attend. This discrete Stingray was pictured by Trent Parke in Coral Bay, Australia, in 2003.