5. Horseshoe Crab
Age: 440 million years
Found in shallow ocean waters and muddy water off the coast of Japan and the east coast of North America, the Horseshoe crab are invertebrates, i.e., they lack a spine. Often used as fertilizer and baits, it mates on land and is considered as “living fossils” like Coelacanth and Frilled Shark in our list of oldest species.