This is the underside of an elephant's foot. The sole of an elephant is full of cracks. Like the fingerprint of people or the stripes of a zebra, those cracks are unique to each elephant. That means, if the tracking conditions are good, that you can identify an individual elephant just by its footprint. The amount of cracks also increases by age, so you can also get an indication of an elephant's age, just from its footprints.
Elephants communicate over long distances with infra sounds, inaudible to the human ear. In the feet of elephants, there are a lot of sensitive nerves that pick up these low frequencies from the ground. So, you could say that elephants can listen with their feet.
