Along with caviar and champagne, oysters are one of the world's most expensive and luxurious .

They are known for their unique flavour and texture, and have been known as a symbol of wealth and sophistication in many cultures for thousands of years. In ancient civilisations they were also an important source of protein for many.

To eat an oyster properly, you're supposed to tip the whole thing into your mouth, straight from the shell, making sure to chew once or twice. But one woman was glad she took a look inside the oyster before eating it - as she was horrified by what she saw.

Taking to , Margo shared a video of an oyster she was about to tuck into - but spotted something moving inside. Someone off camera said the creature appeared to be "swimming, and Margo can be heard saying: "It's trying to find the oyster. It'll go inside of it, so it might disappear in the second."

The person who is eating with Margo could then be heard saying: "I'll never eat an oyster again after this," while they both make noises of disgust. Margo added: "I was just saying how much I live them."

Commenting on the TikTok, which has been seen by 6.2million people, one person said: "Love oysters!! But exactly the reason why I stopped eating them!" while another added: "Welp! I’ve neeverrrrrrr looked at my oysters." A third said: "Omg. I love oysters I'm crying."

Some commenters also shared an explanation about what the moving creature inside the oyster actually is. "Mud worms. Harmless to humans," suggested one person. Another agreed, explaining: "Mud worm, common indicating fresh harvest." A third commented: "Yes I worked at a seafood shop and we had to clean the shells just for this reason but yes, indicates that the oyster is very fresh."

Mud blister worms are one of the many species that burrow into the shells of things like oysters and scallops. According to , assistant Professor of Biology at Clarkson University, the worms "feed by protruding their tentacles out of tiny openings in the shell, where they capture food particles from the surrounding seawater".

But luckily, the "shell-boring worms pose no threat to humans", and even if you eat them accidentally it won't "lead to any health problems".

The National Oceanic and Atmospheric Administration agrees that you shouldn't worry if you accidentally eat one. If you spot one, they recommend wiping the worm off the oyster with a napkin.