>>30470880In alchemy the moon, silver, and mercury are associated with each other to varying degrees and they all represent feminine energy/life
The sun along with sulfur and gold are considered masculine
There is a thought of transmuting the soul which melds the gold and silver into a perfect soul, this is mirrored in the Alola legend of a missing legendary creature that is their love child. Megearna would have thematically and visually made the most sense but didn't have enough "space/alchemy" lore going for it