Spat are picky. They will only live on clean oyster shell or other clean objects underwater. Oysters grow to about 3 inches in 3 years. They will only live in salty water. The oyster begins life as a male changing to a female at about 3 years of age.
Many people like to eat oysters.
For that reason, they are a very important seafood resource for the Chesapeake Bay. Another reason that oysters are important is that they feed on the algae in the Bay. As they eat they act like a filter on a fish tank. Oysters filter out all the algae and tiny particles that cloud the water. Oyster beds or reefs form a suitable habitat for other living creatures.