Ever wonder what the inside of an automated Portal turret looks like? Ever wonder why these things are dumb as a pile of rocks? Concept art from Portal 2 offers insight into both curiosities.

Those lightweight, seemingly infinitely supplied Portal turrets are astoundingly simple in their design. And, as Game Informer's update to the game's concept art shows, they're also incredibly stupid because the gross majority of their inner workings are occupied by bullets.

There's plenty more art where that came from, including a conceptual look at more of the Aperture Science labs and even more turret bots. Please, eyeball them, while we wait for the PC, Mac and Xbox 360 game to ship this fall.

New Portal 2 Concept Art [Game Informer]