Nobert and Queen Potoo as Ometeotl?!
Ometeotl, the god of duality, is a self-created god that divided “himself” into two, a male and a female: Ometecuhtli and Omecihuatl, “Two Lord” and “Two Lady” (Or Tonacatecuhtli and Tonacacihuatl, “Lord/Lady of our Sustenance”). They reside in Omeyocan, the highest of the 13 heavens, and they are responsible for the creation of the four Tezcatlipocas.
The Cosmic Egg is a symbol that appears in several mythologies around the world, specifically in cosmogony. Greco-Roman, Egyptian, Hindu and Finnish creation myths to name a few. They usually describe the world coming from the different parts of an egg, or a creator deity hatching from one, then creating the universe. A summary of some of them with respective links is here.
The Legend Of The Suns is the Aztec creation myth, and it fits Monkey Wrench to have the cosmic egg appear in its pilot, specially as the introduction of the show. I believe this is what the “Ghost Egg” is referencing.
There is no cosmic egg in Aztec mythology, though. The closest thing we have to that is Ometeotl, the self-created god who, as the creator couple, are the “parents” of the main four.
The “ghost” part of the ghost egg comes from the fact that the Potoo family are, well, potoos. The potoos are a bird family found in Central and South America. They have many names, such as kakuy, guajojo, or like in Paraguay, urutau, “ghost bird”.
You can see that Queen Potoo is designed after a potoo bird, whereas Nobert is based on a parrot.
These two have a ghost egg, or a cosmic egg motif. These two serve as the very first bit of foreshadowing of the possible trajectory of the story.
I feel like it’s completely in the spirit of the series to have the two primordial creator gods, the ones that started everything, the ones that are the highest above in the 13 heavens, and make them joke characters. Also, how convenient that they’re voiced by the two creators of the show!
