A bizarre series of events in a college microbiology lab class left 33 people—including students, professors, and lab workers—believing they were exposed to a deadly germ. The microbiology lab students were supposed to be given mystery bacteria by their instructors and then identify the microbe based on a series of biochemical tests and morphological characterization. Unbeknownst to the students, the mystery bacteria was supposed to be Plesiomonas shigelloides, a common, non-scary bacterium. To the lab instructors’ great surprise, no one in the microbiology class identified their mystery germ as P. shigelloides. Instead, every single person in the class identified it as Neisseria meningitidis, a dangerous pathogen that can cause meningitis (swelling of the brain and spinal cord) and bloodstream infections, both potentially deadly.