Naturally occurring stones, often stalactites or stalagmites, which were struck to make music since Palaeolithic times. It is a set of struck sonorous stones (individually called phonoliths) found from the South Seas and South America to Africa and the Far East. Large stones were used in some Vietnamese religious temples and one of the oldest surviving lithophones was discovered there. Remains of other ancient stones come from Chinese archaeological digs, and such instruments are mentioned in sources as early as the Chou dynasty (c. 1122-256/255 BC).