Answer:
I'm white, I'm round, but not always around. Sometimes you see me, sometimes you don't.
Creatures of power, creatures of grade, creatures of beauty, creatures of strength. As for their lives, they set everything's pace. For all things must come to live. Under their emerald embraceย Either in their life or in their death.
Five hundred begins it, five hundred ends it. Five in the middle is seen. First of all figures, the first of all letters. Take up their stations between. Join all together, and then you will bring before you the name of an eminent king.
What is never used unless it's in a tight place?
What looks back but cannot see?
Why is the letter B always cool?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?