meh, i just looked it up... i don't really like it, because i would never consider that a box. still didn't see what book it was from though (didn't really look after i found the answer)
box: a container for objects or dry goods, often with a removable or hinged lid, and usually square or rectangular. Note that it says usually so not always, so the riddle uses the idea of container but not of being square or rectangular.