Answer:
What can go through glass without breaking it?
Large as a mountain, small as a pea, Endlessly swimming in a water-less sea.
I bind it and it walks. I loose it and it stops.
They're up near the sky, on something very tall. Sometimes they die, only then do they fall.
I sleep by day, I fly by night. I have no feathers to aid my flight.
What do angels sing in the shower?