So while browsing the interwebs, and coming upon several Sailor Moon posts here and there, I noticed one thing no one else has pointed out. The two characters who are associated with the Earth element both are represented by a shade of purple. And both have inversions of said element.
Sailor Saturn has powers of destruction, as she is meant to represent a harvester reseting a field. This being based on the Roman God of the same name.
Tuxedo Mask has powers of protection, seemingly representing a cultivator, who protects and nurtures new crops. His association with the sun further supports this; as saplings rely on the sun's warms. This is very similar to the concept of Earth Mothers, despite Mamoru being male.
Both characters also have healing power. Presumably, Hotaru is destroying what's causing the issue, while Mamoru is aiding the natural recovery process. Either way, it's healing, lol.
Just a fun little tidbit I noticed.