According to legend, the Singing Stones were delivered to the Daamin by the Elder Gods in the time before the Pylistroph.
The Stones were 21 in number, of many different colors and shapes. They produced music -- music that was different for each listener, and which could not be captured on physical recording devices. Scientists later devoted millions of years to studying the Stones, and conjectured that the Stones are telepathic resonator/amplifiers. They pick up, focus, and re-project all the thought patterns and emotions that occur anywhere in the Galaxy. The combined concert of all the Galaxy's minds is perceived as the most pure music ever created.
The surviving Singing Stones are kept on Nephestal in Geva Elen, the Place of the Stones, before the Temple of All Worlds. There, the Watchers of the Stones, a cadre of telepathic-sensitive volunteers, attempt to divine meaning from the music of the Singing Stones.
Through the millennia, some specific prophecies have come from study of the Stones.
Information on the individual Stones is here.