Forever enshrined in scientific legend, the discovery of penicillin—a group of antibiotics used to combat a variety of bacterial infections—is really just a case of dirty dishes. Scottish biologist Alexander Fleming took an August vacation from his day-to-day work in the lab investigating staphylococci, known commonly as staph. Upon his return on Sept. 3, 1928, the perceptive scientist found a strange fungus on a culture he had left in his lab—a fungus that had killed off all surrounding bacteria in the culture. Modern medicine was never the same.