Nobel Prize "for the discovery of fullerenes".
The fullerenes are the names given to certain structures of carbon molecule (some of which appear curiously like the shape of a football) whose discovery opened a new field of research due to their stability and versatility. The original discovery opened the door to the uncovering of other structures of carbon based molecules such as carbon nanotubes which allow for the manufacture of extremely heat resistant materials, and as a possible substitute for the silicon used in computer chips today.