"Mellon" was a word Dr. Bart Faulwell used to try and open a sealed door in the cloud City of Stratos, an alternate to the phrase "open sesame" from old Earth literature. (CoE eBook: Signs from Heaven)

This is likely a reference to The Lord of the Rings by J. R. R. Tolkien, where "mellon" ('friend') was the answer to the riddle "Speak friend and enter" at the doors of the Mines of Moria. Faulwell was familiar with The Lord of the Rings as established in SCE eBook: Ring Around the Sky.
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