Bacteria are almost everywhere. Fortunately for our health, most are either harmless or actually helpful to us. Recently, it was proposed that bacteria are eating the sunken Titanic into a pile of rust. Could it be that bacteria are more responsible for rusting iron and steel than is water alone? What to do: You will need some flat pieces of steel (washers are good!), and place them on the surfaces of agar petri plates. Some of your washers will be sterile and others not. Some of the agar will be sterile and others not. If you see rust grow more quickly on the non-sterile ones than on the sterile ones, you'll have proved that bacteria accelerate corrosion. And while you are at it, try other metals. You can buy brass (copper) and aluminum washers also. And don't forget coins! (You might learn why coins usually don't spread diseases.) * For more details: www.science-projects.com/Rust.htm