Which animal lives the longest?

Among animals with a definite lifespan, the ocean quahog clam holds the record: one individual dredged off Iceland, nicknamed Ming, was found to be 507 years old, its age counted from growth rings in its shell. Greenland sharks are the longest-lived vertebrates, estimated to live around 400 years, reaching sexual maturity only at about 150. Some deep-sea glass sponges may live for over 10,000 years. The immortal jellyfish, Turritopsis dohrnii, is even stranger: when stressed it can revert its cells to an earlier life stage and start over, potentially escaping death from ageing altogether.