1. Shelled oysters. Shelled oysters are whole oysters that have not been opened. Shelled oysters need to be steamed for a longer time. Generally, they need to be steamed at high temperature for 8-10 minutes.

2. Unshelled oysters. Unshelled oysters refer to oysters that have had their shells removed, leaving only the oyster meat. This kind of oysters are easy to cook and generally need to be steamed for 3-5 minutes.

3. Half-shell oysters. Half-shell oysters are a more common condition in life. Half-shell oysters are made by opening the oyster shell and dividing it into two halves. They are also the common garlic oysters on barbecue stalls. They are usually steamed. It will be cooked in 6-8 minutes.