Answer:
I am the only thing that always tells the truth. I show off everything that I see. I come in all shapes and sizes. What am I?
By Moon or by Sun, I shall be found. Yet, if there's no light around, I am undone. What am I?
I run smoother than any rhyme I love to fall but cannot climb.
I have three heads. Cut off one I become stronger. Cut off two I become ten.
I welcome the day with a show of light. I steathily came here in the night. I bathe the earthy stuff at dawn but by noon, I'm gone. What am I?
What is lighter than what it is made of?