Answer:
What has to be broken before it can be used?
What measures out time until in time all is smashed to it?
A circle of stones, never in rows. Stacked one on the other, mystery it sows. What is it?
A horrid monster hides from the day, with many legs and many eyes. With silver chains it catches prey. And eats it all before it dies. Yet in every cottage does it stay. And every castle beneath the sky.
I count time, but have no end. Tick tick, but I am not a clock. What am I?
Black we are and much admired. Many seek us if they are tired. We tire the horse, and comfort man, and turn White when we've fulfilled your plan.