In 1928, Scottish scientist Alexander Fleming was working in his London lab when he noticed something odd. A mold had accidentally grown on one of his culture plates of staphylococcus bacteria, and around the mold there was a clear circle where the bacteria had died. Plenty of people would have thrown the dish out as spoiled. Fleming got curious instead. He experimented and found that the mold stopped the bacteria even when diluted 800 times. He named the active substance penicillin. It took years and other scientists to turn it into a usable medicine, but in 1945 Fleming shared the Nobel Prize, and penicillin went on to save countless lives.
