Answer:
It's equally comfortable in an orchestra and a geometry textbook. What is it?
Don't do this in the shallow end.
I can sizzle like bacon, I am made with an egg. I have plenty of backbone, but lack a good leg. I peel layers like onions, but still remain whole. I can be long, like a flagpole, yet fit in a hole.
What loses its head in the morning and gets it back at night?
Describes universities like Harvard and can be poisonous.
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.