Reign of Winter, Maiden, Mother, Crone riddle help

[Nimyue]

For reasons that will take a long time to explain, my PCs are doing the celtic knot configuration when the hut lands in Iobaria at level 10. Because of this, for the test of strength, I'm putting in an adult White Dragon (now it won't be burrowing or flying so the CR is effectively lower I know). However, I need a new riddle.

For anyone not familiar, they need to recover a piece of the monster and the answer to the riddle is that piece.

Does anyone have any ideas?

[Orfamay Quest]

Who are the two brothers who live on opposite sides of the road yet never see each other?

Spoiler:

The answer is "eyes." Bring back the eyes of the dragon.

[StrangePackage]

Dragons have horns, right?

Problem solved.

[Daelen]

It passes before the sun but makes no shadow.

Spoiler:

Air. Cut out and bring back one of the dragon's lungs.

[Nimyue]

Thanks all! Those are really good!