Answer:
To unravel me you need a simple key, no key that was made by locksmith's hand. But a key that only I will understand.
Goes over all the hills and hollows. Bites hard, but never swallows.
Covered in stone and sun. It's home to many but also none. What is it?
What goes further the slower it goes?
Dies half its life. Lives the rest. Dances without music. Breathes without breath.
Iām grown from darkness but shine with a pale light. Very round I am and always a lady's delight.