You’ve probably heard of the Egg of Columbus (Wikipedia: https://en.wikipedia.org/wiki/Egg_of_Columbus).
This is an idiom that describes a brilliant, yet surprisingly simple solution to a problem that was previously considered very difficult or even impossible.
The story goes like this: Christopher Columbus (Wikipedia: https://en.wikipedia.org/wiki/Christopher_Columbus) was being mocked by Spanish nobles at a banquet. They said, “Anyone could have discovered America—it wasn’t that hard.” Columbus then took an egg and challenged those present to stand it upright on the table. No one could. Then Columbus took the egg, cracked it so hard on the table that the bottom was slightly dented, and it stood upright. He said, “It’s quite simple—if you know how.” Here is the image from Wikipedia.
I first saw this in a Donald Duck comic (my blog https://hannosteinerdenkt.de/en/are-the-donald-duck-pocket-books-actually-from-the-usa/) – specifically in “From the Life of the Important Navigator Christopher Columbus” in “Funny Pocket Book No. 123”. You can buy it (used) on Amazon, for example, or view it (for free) on the Internet Archive: https://archive.org/details/ltb123-14bd/page/n101/mode/2up (unfortunately, it’s only in German).
The “egg of Columbus” is very similar to the idiom of “untying the Gordian knot” (Wiki https://en.wikipedia.org/wiki/Gordian_Knot) or to the “Kabayashi-Maru maneuver” (my blog https://hannosteinerdenkt.de/en/kobayashi-maru-maneuver/).