A sample of the original penicillin mould grown by scientist Alexander Fleming has sold for ?�4,649 ($7,154).
The lot was among the highlights of a sale at Catherine Southon Auctioneers in Surrey, UK on July 8.
Fleming made his world-changing discovery in 1928. Penicillin made ailments that had once been fatal easy to treat and continues to save lives around the world.
He gave the piece of the original mould to his neighbours in 1955, after they scared off some burglars that were attempting to break into his home.
He wrote in a note accompanying the lot: "I have to thank you for a great service when on Saturday night you scared the burglars and so saved my safe and its contents.
"I should have been very sorry to have lost all the various medals which have been given to me and after this experience I do not trust the safe - they are in the bank.
"I must apologise for my affairs having given you trouble and again thank you for your help."
A note from Fleming's housekeeper also includes a note that reads: "As though you didn't know - but just in case - this said affair is a blob of the original mould of penicillin, not to be confused with Gorgonzola cheese!!!"
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