Tin foil hats at the ready: alien-hunters reckon they've spotted an alien base lying at the bottom of the Pacific Ocean. The finding was made on Google Earth by Argentinian Marcelo Igazusta, an extra-terrestrial enthusiast, who believes it shows an underwater pyramid structure measuring between 8.5 and 11 miles across.

The sighting was picked up by ET blog UFO Sightings Daily, which claimed the image could alternatively show a UFO parked beneath the waves off the coast of West Mexico. Blog editor Scott Waring called the find "a monumental discovery", likening the structure to the ancient pyramids built by the Myan and Aztec peoples thousands of years ago.

Yet Waring, who also claims to have spotted monkeys on Mars, buildings on Mercury and a Kraken roaming the South Atlantic, doesn't believe these could have been built by human hands. "Humans could never have built such a construction," he said. "Only aliens could accomplish making such a massive structure."

It's hard to make out much from the pixelated Google Earth image, although the pyramid becomes much easier to spot once it's been drawn over the top. If you fancy checking it out for yourself, the coordinates are 12° 8'1.49 'N 119 ° 35'26.39' W.

What do you think – alien megastructure? An unidentified flying object? Or could it be something more Earth-bound, such as waves or the shadows of passing clouds? Let us know @IBTimesUKTech.