NEW YORK (CBSNewYork) — A giant oyster has been discovered in the Hudson River.

It was found last week living underneath Pier 40. It’s not the biggest ever, but at eight inches, it is the largest found in 100 years.

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Researchers say it could mean the river is cleaner than we think.

“It’s actually so large we can really start to see definition in the growth rings here,” said Sidartha Hayes of The River Project.

It is estimated to be 10-15 years old.

The huge oyster recovered from the Hudson River measures 8.5 inches long and weighs 1.3 pounds. (credit: River Project NYC)

This one, the size of a small shoe, was growing on the pier near a construction site. Crews noticed it and turned it into The River Project, a group that studies the species.

“Normally they don’t reach that size before they encounter some type of mortality, whether that’s through disease or something like that,” said Toland Kister of The River Project.

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The species was thriving in the Hudson until the 1900s when over-fishing and pollution destroyed the stock.

For years now, The River Project has been working to help restore the mollusks, which in turn, helps keep the river clean.

“Oysters are filtering the water. They’re clearing it up. They’re actually making a lot more room for sunlight which allows plants to grow on the bottom of the river,” Kister told CBS2’s Natalie Duddridge.

The River Project not only works with oyster preservation but also with dozens of other species found in the Hudson River. The seahorse, for example, is another species that declined drastically in the 1900s but is now successfully reproducing again.

Researchers say it’s further evidence their project is working.

The giant oyster discovered last week will live out its life in its new safe home, away from predators like the toadfish, whose teeth and jaws can crush it, ensuring that it won’t be served for dinner.

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By the way, don’t looking for any giant pearls here. Researchers say this type of river oysters do not grow pearls.