Crocodiles are one of the oldest living creatures on the planet, believed to be around 200 million years old. This means that crocodiles already existed in the time of dinosaurs. As crazy as it sounds, crocodiles are known to swallow stones when they are on the banks of the water. The crocodile does this not only to aid its digestive system but also to improve the buoyancy of the crocodiles in the water. It is thought that by swallowing stones, the crocodile can also swim into deeper parts of the water. Dimensions: 15 x 13 x 8 centimetres. The crocodile's mouth can open and close.