THIS IS RUST. IT IS CAUSED BY OXYGEN AND WATER. WE CALL IT OXIDATION. We breathe oxygen every day. If it can do this to a chain. Just imagine what it can do to your lungs. We also drink water in our daily life. Water is also made of oxygen. After seeing what water did to a metal chain, just imagine what it can do to your body. SHARE TO HELP RAISE AWARENESS ABOUT THE DANGERS OF OXYGEN AND WATER.