Answer:
You can break it or drink water from it.
Deep, deep, do they go. Spreading out as they go. Never needing any air. They are sometimes as fine as hair
Watches students at the prom to make sure there's no funny business.
What is in seasons, seconds, centuries, and minutes, but not in decades, years, or days?
They come out at night without being called, and are lost in the day without being stolen. What are they?
It is something you will never see again.