Most people have heard stories about aliens and some believe that there are no aliens ever exist. According to national enquirer billion of years ago, aliens have been on earth before humans.
The research shows the signs that technological species may exist on our planet and soon it will be revealed the alien technology signatures which were left behind by other species and they were not humans.
As mentioned above billion of years ago, apparently most of the signs or evidence may be gone because planets change with time. They are hoping to get some evidence about alien technology because of erosion and plate tectonics may be they are gone. However; Some proofs are being noted on the surface of Mars and Moon.