Crocodiles are one of the planet’s oldest living creatures, believed to be around 200 million years old, which means crocodiles were already around in the time of dinosaurs. As crazy as it sounds, crocodiles are known to swallow rocks when they are on the banks of the water. The crocodile does this not only to aid its digestive system but also to help the crocodiles’ buoyancy in the water. It is thought that by swallowing stones, the crocodile can also swim to deeper parts of the water.