1. Beneath the surface Undoing our damage to oysters can help ease our impact on everything else. Each one can filter up to 50 gallons of water a day. Replenished beds could help restore the Chesapeake Bay and surrounding lands, a region known for rare birds, horseshoe crabs, and ­agricultural pollution.
  2. At the bottom Larvae need something to hold on to. In lieu of their layered ancestral homes, 40-micron eggs can grow on discarded oyster shells from restaurants. The husks dry out for a year, then get seeded with eggs, bundled into porous containers, and dumped in the harbor.
  3. Along the shore Beaches lose thousands of cubic yards of sand to wind and waves every year. Sand shifts along shorelines naturally, but ­oysters can help ­prevent excess erosion. They slow the surf, ­keeping the ­little golden granules in place—​and protect ­seaside homes from ­flooding.
  4. In the breakers When a wave breaks over an oyster colony, their clustered bodies slow the water, providing a ­natural seawall similar to coral. Bivalve-built reefs once protected vast tracts of the Atlantic coast, but overharvesting and pollution destroyed them. Hopefully we can rebuild these ancient buffers. This story originally published in the Out There issue of Popular Science.