Answer:
What is a five-letter word that has brain in it?
I am seen in the water. If seen in the sky, I am in the rainbow, a jay's feather, and lapis lazuli.
What has four wings but cannot fly and uses the wind but does not know why?
I can be cracked, I can be made. I can be told, I can be played.
I am believed to be only one dimensional, and tinier than anything can be, and there are many who say that I am the basis of all that we see. What am I?
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?