TIL that Penicillin , the first widely used antibiotic was an Accidental discovery by Alexander Fleming .

https://www.sciencemuseum.org.uk/objects-and-stories/how-was-penicillin-developed

https://www.reddit.com/r/todayilearned/comments/15md8s3/til_that_penicillin_the_first_widely_used/