A reverse hourglass is an intriguing timepiece that defies the natural flow of sand through narrow passages. Unlike traditional hourglasses, which fill up as sand trickles from one bulbous chamber to another, a reverse hourglass features two chambers connected by a narrow passageway. As the sands begin to pour from the upper chamber into the lower, time seems to reverse itself, creating an intriguing illusion that the hands of the clock move backward.