Answer:
A great mysterious place that the bold have been known to journey into.
You heart it speak, for it has a hard tongue. But it cannot breathe, for it has not a lung.
What has three ways out and just one way in?
Something wholly unreal, yet seems real to I. Think my friend, tell me where does it lie?
I'm a god. I'm a planet. I measure heat.
You use it between your head and your toes, the more it works the thinner it grows.