NEW YORK (CBSNewYork) – Oysters on the half shell are popular on restaurant menus all over the city – and now shells from the dish are fighting pollution in area waterways.

Madeline Wacthel with the Billion Oyster Project advocates for thriving oyster reefs and creating more diverse sea life, a cleaner harbor, and a stronger shoreline, reports CBS2’s Vanessa Murdock.

“Oysters are ecosystem engineers, they are keystone species,” said Wacthel.

The non-profit is committed to filling the harbor with one billion bivalves by 2035 with a little help from New Yorkers’ appetite for oysters.

A group of 70 restaurants across the city save their leftover shells and instead of sending them to the landfill, give them to the cause to new life.

ALSO SEE: Waste Not, Weather Not: Seafood Shells Being Used To Build Living Reef Off Lido Beach

“We actually grow our oysters on reclaimed oyster shells,” said Wachtel.

Cull & Pistol Oyster Bar in Chelsea Market was one of the first to get on board with giving back.

“It’s a natural fit for us,” said the restaurant’s executive chef David Seigal. “We sell about 30,000 oysters a week and those shells need to go somewhere.

“It’s a good feeling, our customers are really into it,” he said.

ALSO SEE: List Of Restaurants Participating With The Billion Oyster Project

A total of 10,000 pounds pile up per week and ultimately end up on Governors Island.

Chopper 2 spotted mounds of them waiting to be placed in tanks with baby oysters at The Urban Assembly New York Harbor School.

Up to 20 oysters can grow on one reclaimed shell, and eventually growing oysters get moved to one of 13 reef sites around the harbor.

Oysters returned to the harbor are not for consumption. They exist solely to bolster the ecosystem and strengthen the coastline against future storms.

“That’s so cool,” said 14-year-old Jacqueline Lovci. “We need to figure out a way to get involved.”

That’s exactly what the Green Team at West End Secondary School did.

“You’re thinking we are only 11 and 12, how are we going to make an impact?” said 13-year-old Elizabeth Alton.

“We are trying to pass legislation that gives restaurants a tax credit of 10 cents per pound,” said Lovci.

The students’ goal? To add incentive for more restaurants to shell out.