Figure 1
T. Jamin/CNRS Paris Diderot Univ.

Knowing how to fold ‘em. Four frames of a movie (see below) show the changes in a triangular membrane wrapped around a droplet of a ferrofluid as the magnetic field increases from zero (first frame). At a critical field strength, the structure suddenly flips to a new conformation, allowing the fluid cone to rise higher, with the membrane wrapped around it differently (last frame).