Near Chappaquiddick Point lies an unassuming summer house with a big mission. Over the last summer, the Martha’s Vineyard Shellfish Group has converted the two-bedroom home into a shellfish nursery complete with swirling pools of saltwater and millions of baby bay scallops. And although the project is not yet complete, the hatchery has already helped raise millions of tiny shellfish for distribution to the Island’s coastal ponds.