In the recent Global Energy Breakthrough Conference in Boulder, Colorado, Michael Tellinger shared his theory that sound is one of the most abundant forms of free energy on the planet. He said that sound is the primordial source of all things and is the common denominator of all creation. With that being said, if an extraterrestrial race wanted to harvest energy from the planet, it could create such energy with sound.
Some channeled information confirm this and inform, that the pyramids have been constructed with sound devices. The Ankh is maybe such a sound device in form of a kind of sound pistol. This would explain how ancient constructions like the Pyramids or Stonehenge could be built with such a precision.
Three-Dimensional Mid-Air Acoustic Manipulation [Acoustic Levitation]