Open, as oysters refers to the process of shucking, which is the act of opening an oyster shell. Shucking is done by inserting a knife or other tool into the hinge of the oyster and then twisting it to open the shell. This process is necessary in order to access the edible meat inside the oyster. Shucking is a skill that requires practice and patience, and is often done by professional shuckers in restaurants and seafood markets.