The Song of Angels is an ancient artifact located in the Catacombs of Fornae and used by the Froziarii. It is a data storage unit that gave them much valuable insights on shipbuilding, lightspeed travel and A.I. programming. Most of it was translated into their language hinting that it could've been placed by a race that had plans with the Froziarii and wanted them to advance at a faster pace.
Determing from the looks of the machine it could be from the planet Sosz where an ancient city was discovered that houses the same machines but those were too badly damaged.