[Unknown_Sniper]

its a giant inter stelar nuclear weapon never fired at us. you can cleary see how this is true because the entire planet was scorched and flatened by a massive nuclear bombardment. That explains the different in color, the weirdness of the planet and that yet unfired nuke sitting on the bottom of the planet.
now ion reality I would say this guy is a fucking nut case. Clearly those "90 degree angle walls" are in fact hills with a shadow on one side making them look like they are narrow walls. The scorched ness and the ring i nthe center and the weird shape are probably due to an encounter with an asteroid millions or even billions of years ago. Now if that planet did house life which at one point it could have then awesome can wait to get there. But until we know for sure, that guy is a grade A loony.