[omega4412]

I believe that Fleming's discovery that led to penicillin was partially an accident.

The story is that before Fleming's work other researchers saw mold killing bacteria but just thought "Dang! That mold is killing the bacteria I'm trying to grow. Have to start over and be more careful."

[boop]

Fleming left the window in his lab open one night and some spores got blown into his culture dishes. The mold killed his cultures, like you said, and he became interested in the "why" it did the killing.

Another thing that is interesting is the noting that Cancer cells can be "immortal" in the lab, because they grow so fast. There are cells called He-La, that were grown from a woman's cancer for years after she died.