Takamizawa and Miyamoto2 pushed a metal blade against a single crystal of terephthalamide and observed how the crystal underwent reversible deformation. The crystal is initially in a crystallographic phase known as the α phase (a). When the blade is pushed against the crystal and the stress applied by it reaches a constant value, the crystal undergoes a phase transformation into a β phase at the contacting area between the blade and the crystal surface. This phase grows first along the pushing direction of the blade (b) and then perpendicularly to this direction, bending the crystal at the interface between the two phases (c–e). When the blade is pulled back, the crystal undergoes the reverse transformation (f–h), ultimately returning to its initial form (i). The top-right black region in these microscopy images is the blade, and the black region on the left is the glue used to fix the crystal to an underlying stand.