Oysters can help save the planet: (a single oyster can filter 50 gallons of water every day, and a healthy one-acre reef filters around 24 million gallons) but by filtering they also absorb carbon, which they turn into calcium carbonate to strengthen and grow their shells. The oysters also absorb nitrogen, a greenhouse gas that affects our environment, and an oyster reef or farm of about 3 acres’ worth of water space, can account for absorbing the nitrogen waste of up to 35 people.