Is an ancient civilisation lurking behind the 'door' Curiosity rover found on Mars? NASA answers

The internet has been abuzz since NASA shared images of what appears to be a doorway cut into a cliff on Mars.

NASA said that while the structure is fascinating, it is perfectly natural rather than the work of aliens, but that hasn't stopped netizens from going wild with theories.

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The 'doorway' was found on Mars on May 7 in an area the Curiosity rover has been exploring since 2012. The structure is a fissure and only 12 inches tall and 16 inches short — roughly the size of a 'dog door' hence earning the nickname from NASA.

NASA in a statement said such structures are commonplace on Earth as well as Mars. The statement added that it may 'look' like a door as the mind is trying to make sense of the unknown. NASA added that while there is likely no civilization lurking behind the 'door', the odd crack may provide an interesting opportunity for new science, calling it a 'door' to the ancient past.