Man walks over, man walks under, in times of war he burns asunder. What is it?

I dance without a heartbeat, I bow without a mind, My spine is crossed by silver veins, My thoughts are left behind.

When rain falls heavily, I catch its song, a chorus in tin or plastic. I carry builders' dreams and children's beach castles, yet I am empty without your hands.

Look inside my borders Four kingdoms I contain Each with equal power But a different claim to fame One is rich with gemstones Another dug them up The third is known for lovers The last for being tough Outside of these four kingdoms A clown or two remain They mingle with each other Forever playing games

I start as sap from forest veins, then heat transforms my polymer chains. I stretch, return, and still endure, made strong and flexible through fires cure.