Shape-shifter molecules are in never-ending motion. Their structure fluctuates because the carbon bonds that hold them together constantly break up and form again. Researchers have now found a way to "tame" a shape-shifter molecule called bullvalene. In the journal Angewandte Chemie, they report that integrating the molecule into a coordination cage enables its shape-shifting behavior to be restricted through molecular recognition. Such form capturing could play a role in responsive materials.