What is "hidden color"?

[eye_of_the_world]

Peacock- purple with hidden yellow
Dawn tree (expired)- green with hidden white
Kitsune- pink with hidden red
Black swan- pink with hidden black
Night elf- black with hidden purple
Atlas- mythic with hidden green/blue
Saturn (expired)- cosmic with hidden green/blue
Eclipse (expired)- cosmic with hidden black
Cheshire (expired)- fairytale with hidden pink
Big bad (expired)- fairytale with hidden black

Saturn is Cosmic with hidden Red and Yellow
Eclipse is Cosmic with hidden Black and White (Moon, was the only one that could be used back then)

Golem- stone with hidden black
Mossrock- stone with hidden green
Turquoise- stone with hidden blue
Rex- Dino with hidden red
Triceratops- Dino with hidden green
Pterodactyl- Dino with hidden yellow
Virgo- Leo with hidden purple

Naga- pink with hidden green
Shell- tropic with hidden pink
Turtle- tropic with hidden green

I think that's it! Anyone let me know if I forgot any.

I think all the others are correct though.