Answer:
What is a five-letter word that has brain in it?
Sleeping during the day, I hide away. Watchful through the night, I open at dawn's light. But only for the briefest time, do I shine. And then I hide away. And sleep through the day.
I am round as a bowl, deep as a tub, but all the world's water couldn't fill me up.
What doesn't get any wetter, no matter how much rain falls on it?
What measures out time until in time all is smashed to it?
This food is a tortilla filled with cheese and sometimes chicken before being heated or cooked.