We’re suckers for a fluid that can dance. These magnetic water droplets, or ferrofluids, can switch between a static self-assembling state—in which the structure organizes itself when the system reaches an energy equilibrium—and a dynamic state, in which the self-assembly is driven by continuous energy.

Researchers at Aalto University in Finland and ESPCI Paris Tech created the model. It can reverse from static to dynamic and back again with an oscillating magnetic field.

“Over the years we have managed to create functional materials based on static self-assembled hierarchies. This model system paves the way towards even more versatile dynamic materials, wherein the structures are formed by feeding energy,” one of the researchers involved, Olli Ikkala, said in a press statement.

Cool for physics nerds, but pretty mesmerizing for anyone else, too:

See the state-switching in action:

For more info, check out the research in Science.