Plutonium (Photo: Department of Energy/Wikimedia)

After World War II ended, chemist and Manhattan Project member Glenn Seaborg finally got to add Plutonium, the element he had discovered during the war, to the periodic table.

As Robert Krulwich recounts at National Geographic, Seaborg also chose the short-hand symbol for plutonium: Pu.

There’s something strange about that decision. A more obvious choice would have been to have Pl as the element’s symbol. But, as Seaborg’s son told Krulwich, “‘he just thought it would be fun’ to treat this element as if it were stinky.” So, he chose P and U, as in: Pee-yew, that stinks!

This wasn’t meant to be a political statement, according to Krulwich. It was just a joke! One that will last for as long as the periodic table, a (rotten) easter egg just waiting to be discovered.

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