Answer:
What does everyone know how to open but not how to close?
What can you fold but not crease?
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 don't think or eat or slumber. Or move around or fear thunder. Just like you I look the same but I can't harm you or be your bane.
I am the yellow hem of the sea's blue skirt.
They are many and one, they wave and they drum, Used to cover a state, they go with you everywhere.