The world’s oldest animal just got even older.

A mollusk discovered in Iceland in 2006 was believed to be around 405 years old, but researchers recently took a second look at the mollusk, a type of deep-sea clam, and discovered the animal is 100 years older – a ripe 507 years old.

“We got it wrong the first time, and maybe we were a bit hastily publishing our findings back then. But we are absolutely certain that we’ve got the right age now,” Paul Butler, who studies the particular kind of mollusk at Bangor University in Wales, told ScienceNordic.

At the time of its discovery, the ocean quahog, also known as Arctica islandica bivalve mollusk, made it into the Guinness Book of World Records as the world's longest-lived non-colonial animal. Scientists named the mollusk Ming, after the Ming Dynasty which ruled in 1499, the year it was born.

The discrepancy over the age came from the method researchers used to date the animal. Scientists determine the age of ocean quahogs from the number of rings on the interior of their shells. But since Ming was so old, the rings were compressed to only a few millimeters apart, leading to an inaccurate reading. When scientists decided to revisit Ming’s age, they decided to look at the rings on the outside of the shell since they were more spread out.

To make sure they had the correct time period, researchers not only used carbon-14 testing but also compared their findings with other quahog specimens from the same era.

“The ocean quahog specimens we used for comparison were obviously not as old as Ming, but they have lived in different periods of Ming’s life. So this is how the patterns in their growth rings can help verify the age,” Butler said.

The secret behind Ming’s longevity may lie with its metabolism. “The A. islandica has a very low oxygen consumption. When an animal has such a slow metabolism, it normally also means that it has a very long lifespan. However, I also believe that part of the reason for its longevity lies in its genes,” German animal physiologist and marine biologist Doris Abele said.

Beside the animal’s remarkable age, it may offer clues on climate change. The oxygen isotopes on the mollusk’s growth rings can determine what the ocean temperature was when the animal was born.

“There are a number of methods to chart past climate on land, but for the marine environment we only have some very limited data. The A. islandica can help fill this gap in our knowledge and provide us with a very accurate picture of past climate,” Rob Witbaard, of the Royal Netherlands Institute for Sea Research, said. “This is important to our understanding of how much changes in the oceans affect the climate on land. And the really amazing thing is that the pattern in the ocean quahog’s growth rings actually recurs in tree rings.”

Iceland Climate change