Of course this unusual Mars rock is probably just a trick of light and random erosion, but it is sufficiently regular to allow one to imagine that we might not understand Mars nearly as well as we think we do. We’re not making any claims about the object beyond saying that it is as regular as if it had been carved, seems out of place in its surroundings and appears to be part of something that is buried. If a photograph like this was taken in a desert on Earth, the only question would be, ‘who carved it?’

Story Source:
http://www.dailymail.co.uk/sciencetech/article-2769279/The-red-yellow-green-planet-Strange-traffic-light-shaped-rock-spotted-Mars.html