These are planters in the form of tetrads. They are equally suited for growing shit or use as cereal bowls. And, because I'm a complete slaya', I've even come up with another use: decoration. Did I just blow your mind? No? THEN WHOSE WAS THAT? Quick -- the lights!
Tetris Goes to Pot [kotaku]
Thanks to Julian, who grows his 'grass' in old milk jugs like a normal person.