Ancient Aliens is counting down the world's top ten mysterious devices, from strange, grooved disks found in a cave in China to an ancient Greek computer to an incredible crystal skull unearthed in Mexico. Might these sensational artifacts provide evidence of extraterrestrial visitation?

Around the world and throughout history, people have reported seeing very similar types of unidentified objects in the sky. Now, Ancient Aliens is counting down the top ten alien craft, from V-shaped objects to orbs of light to flying saucers. Could the ubiquity of these sightings provide evidence of extraterrestrial visitation?