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Carbon is a shapeshifter. When its atoms bond to four neighbors, it becomes diamond. With three bonds, it transforms into sheetlike graphite or graphene, 3D nanotubes, or even soccer ball–shaped buckyballs. But no one has ever put together a stable arrangement where each carbon has just two neighbors—until now.

Chemists in Switzerland and the United Kingdom started with a triangle-shaped loop of 18 carbon atoms, with two carbon monoxide (CO) groups at each corner to provide stability. The chemists then used the tip of an atomic force microscope to zap off the CO groups, eventually removing them all to create their 18-carbon ring (simulated above). The new molecule, known as a cyclocarbon, is the smallest theoretically stable ring of carbon to exist, they report today in Science.

The carbon ring is also highly reactive, allowing the researchers to fuse it with other carbon and oxygen rings. That has already led to one other novel compound, and it has opened the door to a wide array of novel ring-shaped structures that might one day be used in electronics and other nanodevices.