This is the Chladni plate experiment. It uses a tone generator, a wave driver (speaker), and a metal plate attached to the speaker. Sand is first added to the plate, then a tone is played. Certain frequencies vibrate the metal plate in such a way that it creates areas where there is no vibration. The sand “falls” into those areas, creating beautiful geometric patterns. As the frequency increases in pitch, the patterns become more complex.
(via Laughing Squid)