  We present and analyze a minimal hydrodynamic model of a vertically vibrated
liquid drop that undergoes dynamic shape transformations. In agreement with
experiments, a circular lens-shaped drop is unstable above a critical vibration
amplitude, spontaneously elongating in horizontal direction. Smaller drops
elongate into localized states that oscillate with half of the vibration
frequency. Larger drops evolve by transforming into a snake-like structure with
gradually increasing length. The worm state is long-lasting with a potential to
fragmentat into smaller drops.
