Staten Island, N.Y. - Massive cargo ships pass through the waters of New York Harbor every day, speed boats cruise by, and the Staten Island ferry shuttles passengers back and forth to Manhattan, 24/7. 

But in the midst of that — some middle school students excitedly squeal about what they’ve just pulled out of the water.

The students are monitoring eight oyster cages dangling off a pier in the harbor. The goal is to determine if the oysters in the cages grow and to see what kind of marine life they attract. The findings will say a lot about the harbor's water quality.

"The animals that we find are really cool," said Julia Barrett, a 7th grade student. "The fish, we had a really big crab that we found inside. Just like the animals that come into the cage are really fascinating."

The students are participating in the Billion Oyster project, a 20-year project to restore the harbor's once-abundant oyster population. 

Beyond purifying the water, oyster reefs can soften the blow of large waves, reducing flooding and erosion caused by major storms.

The oysters also attract other marine species improving the biodiversity of the harbor.

Students and researchers hope to learn whether a spot on Staten Island's North Shore — with its busy harbor traffic — would be an ideal spot for an oyster reef. 

"If you collect data in small batches like we’re doing here, you can compare the growth rates here with other places in the harbor, try to find out where the best place is to put our bigger reefs," said Rob Buchanan of the Billion Oysters Project.

Students are measuring oyster growth every three months. And so far, they’ve found the oyster growth is about average. Researchers say that’s not cause for concern.

And they’re encouraged by what else they’ve found in the water.

"You can’t really feel them, but they’re slimy if you touch it with your regular hand," said Annivone Baez, a student.

"There’s a lot of fishes that we see, and crabs. It means that the waters around Staten Island are clean enough to support this biodiversity around the waters," said Pat Wong, a teacher at PS 21.

And that’s good news for Staten Island. 

The students will document their findings which will be passed on to students until the research project concludes in 2035.