Alexander Fleming, a professor of Bacteriology at St. Mary's Hospital in London, didn't do a great job of cleaning his laboratory before heading out on vacation in 1928. When Fleming came back, he began cleaning the petri dishes on which he was experimenting with bacteria. On one dish, however, he found a mold growth. In the area around the mold growth, there was no bacteria. There was bacteria in other parts of the petri dish, but the mold was sitting in an area alone. Fleming had a "eureka!" moment, as he had just accidentally discovered an antibiotic. Learn more about his world-changing discovery with the videos below.
This article first appeared on Curiosity.com.