Answer:
I am a protector. I sit on a bridge. One person can see right through me, while others wonder what I hide. What am I?
I climb higher as I get hotter. I can never escape from my crystal cage.
I pass before the sun, yet make no shadow. I'm all around you, but you cannot see me. What am I?
I am full of holes but still holds water.
If I drink I die. If I eat I am fine. What am I?
It flows out of the soil, It burns you if it boils, And holds us in its coils, More valuable than gold, As black as it is old.