Answer:
Cold head and feet; round as a ball; always turning around myself.
I walk on 4 legs in the morning, 2 legs at noon, and 3 legs at night. What am I?
I am an instrument capable of making numerous sound but cannot be touched or seen.
I am a precious stone, as clear as a diamond. Though you can walk on water with my power, try to keep me, and I'll vanish in an hour. What am I?
Of the king I am blue and of the peasant I am red. Of the frog I am cold and of the dog I am hot instead. What am I?
No matter how little or how much you use me, you change me every month.