Movie 3. Snail-like motion on a surface with many scales. This movie shows the motion of a hydrogel rod on a thin elastic polydimethylsiloxane film subject to harmonic lateral vibrations. (The substrate is vibrated sinusoidally, except when otherwise mentioned.) Many "scales" are scored on the elastic layer, all aligned in the same direction, which serve to rectify the motion of the gel. The scale spacing is ≈3 mm. Frequency, 100 Hz; displacement amplitude, 0.27 mm; filament length, 2 cm; filament radius, 2.25 mm.