BOSTON —They were born from a local company’s desire to protect the shoreline they love. And the source for the sweaters they developed is definitely unusual.

“They’re shocked every single time,” said Mike Lamagna, the founder of Long Wharf Supply Co.

Shocked because every sweater in the “Seawell Collection” contains about four or five oyster shells combined with approximately eight water bottles.

Lamagna grew up on the water around Newburyport and is passionate about reducing waste and protecting our oceans. That’s how he came up with a sustainable and stylish fashion line.

“Every piece can reseed up to 30 oysters which will naturally filter up to 1,500 gallons of seawater every single day,” he said.

By putting oyster shells into sweaters, they’re keeping them out of landfills where the calcium carbonate in the shells breaks down very slowly and can become toxic.

Theresa Baybutt and the nonprofit organization MA Oyster Project have been working to get recycled oyster shells back into the water since 2008 — and for more than one reason.

“By getting it back into the water, it also adds to the substrate for these baby oysters to attach to and grow,” Baybutt said.

We all benefit from that, she said. Oysters feed by filtering algae from the water. In fact, one adult oyster in the wild can filter up to 50 gallons of seawater a day. When the oysters cluster together, they provide an environment for 200 other marine species.

That cycle has been disrupted, in part, due to climate change. Warming waters, more intense winter storms and bigger boats have eaten away at huge underwater reefs that protect our shores. But groups like MA Oyster Project are working year-round to build them back.

A portion of the proceeds from each sweater made by Long Wharf Supply Co. goes to help that effort.

“For us to be able to create a recycled product, pull waste out of the waste stream, make a piece that people love and then be able to reseed oyster reefs in the communities we love most with every purchase, that’s what come full circle for Long Wharf as a brand but also for me as someone who has grown up on the water my entire life,” Lamangna said.