Answer:
In a tunnel of darkness lies a beast or iron. It can only attack when pulled back. What is it?
Open me, and you can't see me without a mirror. Close me and you can't see me at all. What am I?
I am the key that is the hardest to turn
I am a tale in childrens' minds. Though an illusion, I occur every night. I give them a fantasy, I give them a fright. What am I?
I keep growing and am practically indestructible. I get eaten, but always come back. I survive cold and lie everywhere. You see me everyday. What am I?
The answer I give is yes, but what I mean is no. What was the question?