Answer:
I'm white and used for cutting and grinding. When I'm damaged, humans usually remove or fill me. For most animals I am a useful tool. What am I?
I start new then become old. Start clean but be one dirty. I usually start big then become little.
I am asleep when you are awake I am awake when you fall asleep. I can fly but no feathers to aid my flight.
I am made by nature soft as silk; A puffy cloud white as milk; Snow tops this tropical crop; The dirtiest part of a mop.
I am a seed with three letters in my name. Take away the last two and I still sound the same.
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?