There are many kinds of steamed oysters, such as steamed with shell, steamed with half shell, or steamed only with oyster meat, depending on your own needs. Oysters with shells are hard and have small gaps, so they can't contact with water vapor well, and hot air is difficult to penetrate. Therefore, the steaming time is generally longer, and it usually takes 5-7 minutes to open the shell after the water is boiled. If the volume of oysters is relatively large, the steaming time can be extended to 10 minute.

Generally, oysters with shells are closed before steaming, but in the process of steaming, due to the stimulation of high temperature and the need of oyster breathing, they will slowly open their shells. After steaming, due to the degeneration of muscle tissue, it is impossible to control the normal closure, so generally speaking, oysters will open after steaming. Of course, there will be very few oysters or dead oysters that don't open their mouths after steaming.

If there is no opening after steaming, it is recommended to break it with a knife. If the meat quality has not changed and there is no smell, then oysters without openings can still be eaten. However, if the shell is opened and the meat is obviously deteriorated, such as odor and discoloration, then the oyster without shell can no longer be eaten, otherwise it is likely to cause food poisoning.