Answer:
Round like a dishpan and smaller than a bathtub. But the ocean can't fill it. What is it?
I have an eye but cannot see, You'll head inside when you see me.
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.
I am a span of time you can always see through I am also the timepiece with the most pieces. What am I?
I tremble at each breath of air, and yet can heaviest burdens bear.
The warmer I am the fresher I am.