Ming, the mollusk, was estimated by by a team of researchers to be 507 years ago, making it the oldest living animal recorded. Ming is a quahog or clam. You can tell the age of the clam by counting the rings in its shell.
Aging a quahog is essentially the same as aging a tree. Unfortunately scientists opened up Ming’s shell to count the rings, killing it in the process. Some scientists speculate the the cold waters in which the quahog is found slow down its metabolism, leading to improved longevity.
http://sciencenordic.com/new-record-world%E2%80%99s-oldest-animal-507-years-old
Another animal well known for its longevity is the tortoise. Harriet the the Galapagos Tortoise was collected by Charles Darwin in 1835 and died in an Australian zoo in 2006 at the age of 175. Adwaita, an Aldabra tortoise also died in 2006 at an estimated age of 255.
These examples lead to the natural question of why there is an upper limit to an animal’s lifespan and is there something that we can do about it. The answer to this is perhaps found