Frankfurt Zoo isn’t just one of the top 10 zoos in Germany, it also has one of the most beautiful aquariums. But most visitors don’t know about it.

All they needed was a smartphone with QR code reader and a piece of plastic film, which was sticked on the ad. By bending the film into a pyramid and placing it on their mobiles, people created a mini-aquarium with its underwater inhabitants as a 3-D projection.