If you are feeling your age, then spare a thought for the Greenland shark.
A team of scientists has discovered the giant fish can live to be 400 years old, with one female estimate to be 392 years old.
This means that a shark swimming in the North Atlantic today could have been born in 1624 - the decade the Mayflower carried the Pilgrim Fathers to North America, and not long after William Shakespeare penned his best-loved plays. She would have been a youngster when the Declaration of Independence was signed and would have lived through two World Wars.
The incredible discovery makes the species, which can grow up to 21 feet long, the longest living vertebrate known to science.
An international team of scientists led by the University of Copenhagen and including the University of Oxford said the shark's life expectancy exceeds even bowhead whales, turtles and tortoises, the latter of which can reach 100 years of age.
While the Greenland shark is among the world's largest carnivorous sharks, with adults reaching more than 5m in length, the animal's general biology is described in the paper, published in the journal Science, as being "poorly understood" by scientists.
They are among the slowest swimming sharks but are also an apex predator, preying on a range of different fish and smaller sharks.
The longevity of the Greenland shark, which is widely distributed across the North Atlantic, has been a particular mystery for marine biologists for decades.
Traditionally, the age of sharks and rays is determined by counting the seasonally deposited growth layers in hard calcified structures such as fin spines.
But such techniques cannot be applied to the Greenland shark because it lacks such "hard" structures.
To solve this mystery of the animal's life span, the researchers analysed the eye lens nucleus of 28 female sharks, which were accidentally caught during the Greenland Institute of Natural Resources' annual fish and shrimp surveys.
The centre of the shark's eye lens nucleus is composed of metabolically inactive tissue, which does not change significantly from the time of their birth.
This means its chemical composition can be used to reveal the age of the shark.
The researchers measured radiocarbon content of the lenses from which they could estimate age by matching the data to measurements showing radiocarbon changes in the marine food web in the northern North Atlantic over the past 500 years.
Scientists have used tissues from the eye lens nucleus in previous research to estimate the age of whales, but this is the first time that scientists used the method to date the longevity of a fish.
Lead author of the study, Julius Nielsen from the University of Copenhagen and the Greenland Institute of Natural Resources, said: "We used established radiocarbon methods but combined them in a new way.
"This approach, along with the extraordinary ages for these sharks, makes this study highly unusual."
Study co-author Christopher Bronk Ramsey, Professor of Archaeological Science at the University of Oxford added: "We had to take into account the complexity of the oceans and the growth patterns of the sharks when interpreting the data from this project.
"Without the advances in statistical analysis made in recent years, it would not have been possible to demonstrate the extraordinary longevity of this species."
The experts already suspected the sharks could reach a ripe old age because of their large size and slow growth - the ferocious-looking fish grow no more than 1cm a year.
They estimated the two largest sharks examined in the survey - measuring 4.93m and 5.02m respectively - were roughly 335 and 392 years old.
The team came to the conclusion the lifespan of a fully grown Greenland shark female over 5m in length is at least 272 years.
They also estimated that females are around 156 years old when they arrive at sexual maturity, meaning they enjoy a very long "childhood".
Nielsen said: "Greenland sharks are among the largest carnivorous sharks on the planet, and their role as an apex predator in the Arctic ecosystem is totally overlooked.
"By the thousands, they accidentally end up as by-catch across the North Atlantic, and I hope that our studies can help to bring a greater focus on the Greenland shark in the future."
World's longest-living animals
African elephants - Average lifespan of 70 years
Bowhead whale - Average lifespan of 200 years
Galapagos giant turtle - The longest living was 152
Greenland shark - Life expectancy of at least 272 years
Long-finned eel - Often live to over 60
Ocean quahog - Some collected specimens of this shellfish have been calculated to be more than 400 years old
Black coral - Those known as Antipatharia, these coral found in the Gulf of Mexico may live more than 2000 years while the those from the genus Leiopathes are thought to lived for around 4265 years