It took Samuel Stupp years to build the layer cake of mushrooms you see here—or rather, to find a way to let it build itself. The building blocks, says Stupp, a chemist at the University of Illinois in Urbana-Champaign, are molecules called rodcoils, which he did build himself by conventional chemical methods. Rodcoil molecules consist of short chains of carbon: one end is a rigid rod while the other is a floppy ribbon. Stupp discovered that when he dissolved those molecules in a liquid, then let the liquid start to evaporate, the rods attracted one another and spontaneously formed a thick bundle, while the floppy ends formed a spongy dome over the bundle. And if he let the liquid completely evaporate, he got trillions of mushrooms nestled in neat layers. It’s hard to synthesize big molecules using conventional chemistry, says Stupp, who reported his discovery last April. But here you have molecules that are programmed to organize themselves into a nano-size object. Stupp believes this may be a step toward using self-assembling molecules to perform complex tasks. He has already begun testing the mushrooms as a spray-on deicing chemical for aircraft. The stem end of the mushroom, says Stupp, would stick to the airplane, while the other would prevent the formation of ice crystals.