Scientists at the University of North Carolina at Chapel Hill have constructed the smallest ice cube in the world. It wouldn't be much help in chilling a gin and tonic, however, because it contains only six molecules of water. The group was studying water's interacting hydrogen bonds, which control much of biochemistry. It used liquid helium in a process that produced hexagonal rings of ice, mimicking the way ice exists in nature. The tiny cube helps simplify its work because a single drop of water contains about 100,000,000,000,000,000,000 molecules.