Answer:
A circle of stones, never in rows. Stacked one on the other, mystery it sows. What is it?
It is weightless, you can see it. If you put it in a barrel it will make it lighter?
Round as an apple, deep as a cup, and all the kings' horses can't fill it up. What is it?
I am whole but incomplete. I have no eyes, yet I see. You can see, and see right through me. My largest part is one fourth of what I once was.
I love to dance and twist and prance. I shake my tail, as away I sail. Wingless I fly into the sky.
People take me on walks and I run and have fun. What am I?