Answer:
I am the greatest teacher out of them all, but alas in the end I kill my pupils.
I am nothing but holes tied to holes, yet am strong as iron.
The older they are the less wrinkles they have.
Thousands lay up gold within this house, But no man made it. Spears past counting guard this house, But no man wards it.
What can be swallowed, But can also swallow you?
In your fire you hear me scream! Creaking and whining yet I am dead before you lay me in your hearth.