What Am I Riddles

Question: I break down buildings I crumble mountains You can't see me What am I?

Question: Eight of us go fourth, not back, to protect our king from an attack. What are we?

Question: It dies when it's hot, exists when it's cold, you can touch it, but you cannot bounce it, and it doesn't give you any gold. What am I?

Question: Cut my skin out. I'm not going to cry, but you will! What am I?

Question: When it is alive we sing, when it is dead we clap our hands. What is it?