Yes Because the shell of oyster is thick, it is difficult to transfer heat to the inside of oyster meat quickly if it is not pried open, so it takes a long time to reach enough temperature to kill bacteria and parasites inside and ensure the taste of oyster meat. However, because there is basically no sediment in the oysters raised by hanging or purified by merchants, they can be steamed directly without prying them open, but it will take a long time.