Answer:
What weaves webs as they grow?
What do you throw out to use and take in when you're done?
My teeth are sharp, my back is straight, to cut things up it is my fate.
A precious stone, as clear as diamond. Seek it out while the sun's near the horizon. Though you can walk on water with its power, try to keep it, and it'll vanish in an hour.
I always run but never walk, I sometimes sing but cannot talk, No head on which a hat to place, You always look me in the face.
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.