Cymatics is the study of wave phenomena through vibration and resonance. It is a science that was pioneered by Swiss medical doctor and natural scientist, Hans Jenny (1904-1972). The eighteenth century German physicist Ernest Chladni experimented with patterns by showing how sound waves affect grains of sand in a vibrating metal plate. He passed a violin bow along the edge of the metal plate to show that different musical tones caused the grains of sand to move into geometric patterns resembling the mandalas used in eastern spiritual traditions. The patterns formed depending on the physical characteristic or composition of the metal plate itself.
Here is a brilliant video demonstrating this magnificent phenomenon: