Age: 580 million years
Bet you have seen sponge, but it never occurred to you how old it’s origin goes. The organism is not exactly an animal, but it’s definitely one of the oldest species in the world. It does not have any digestive or circulatory systems or even a nervous system. Fossils of prehistoric sponges have been found in rocks, and their origin dates back from 530 to 490 million years ago. Constant water flow is the most important thing in their life, as it helps fetch food and takes care of body waste.