Answer:
What is full of holes, but can still hold a lot of water?
It is worldwide, but once only a spider could weave one
What has a mouth but can't chew?
What surrounds the world, yet dwells within a thimble?
A circle of stones, never in rows. Stacked one on the other, mystery it sows. What is it?
How can you add eight 6s together so that the total adds up to 750?