Because most of us don’t buy our fish straight off the dock, finding a worm with your fresh fish is bound to be a bit of a surprising event. And while a Costco customer’s video of a fresh package of cod doesn’t show the kind of wriggling worm you’d put on a hook, seeing a parasitic nematode snuggled in there is still enough to warrant a “careful if you’re eating lunch while reading this” warning.

The video (seen here, but again, it’s your lunch you’re risking) shows a parasitic roundworm known as a nematode doing a little worm dance inside a package of fresh wild pacific cod fillet earlier this month at a South Carolina Costco, and has shot to viral status since it was first posted to Facebook.

So should you be worrying checking every package you pick up carefully, or this one of those wild and wacky isolated incidents? Well… you should probably check, as a Costco spokesman confirmed the nematode finding and told WSPA.com this isn’t a rare thing by any means.

“Although it’s, quite frankly, disgusting, I wish I could tell you it’s very very uncommon,” Vice President of Quality Assurance and Food Safety Craig Wilson for Costco told the news station.

He adds that ground fish like cod and sole are particularly susceptible to nematodes, but that the company tries its best to nab’em all before they get to you, with fish going through a process called “candling” that involves laying them out on a lit table.

“Around these conveyor tables are employees of the seafood company that are doing nothing but looking for parasites,” said Wilson, adding that the fish in question wasn’t sold, and was instead removed by managers.

You’re probably wondering whether its safe to eat fish that have been packed with these little stowaways, and Wilson says it’s totally fine, there’s no health risk to humans — unless you eat the parasite along with the raw fish. Or eat the parasite without it, don’t do that. Make sure to cook your seafood fare thoroughly before eating.

Fear of parasites is probably why Frodo looks so concerned here:

Worm In Package Of Fish At Spartanburg Costco; Video Goes Viral [WSPA.com]

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