For some people in the Japanese coastal city of Gamagori, the first bizarre warning came by text message on Monday. Others heard it over loudspeakers typically used to warn people about impending earthquakes or nuclear disasters.

But this warning was about fish parts.

Blowfish parts to be exact. A local supermarket had mistakenly sold several packages containing blowfish liver, which can cause a quick death by asphyxiation, and authorities wanted everyone to know about the danger potentially lurking in their grocery bags.

If eaten, the fish could kill faster than an earthquake or nuclear radiation. A suspicious person who bought one of the packages took it to a health center, alarming authorities, according to NPR. And with that, the search was on to find whoever had purchased the nondescript, plastic-wrapped Styrofoam trays.

Blowfish, also known as the dish fugu, is an expensive winter delicacy that requires a special license to prepare because, if handled incorrectly, it can kill the person eating it.

Blowfish are best known for the way they ward off things that want to eat them — by gulping up large amounts of water and expanding to several times their normal size. But they’re not all bluster. Many are brimming with poison, which can kill a large swath of potential predators, including patrons at fancy restaurants forking out hundreds for fugu.

The liver of some blowfish contain tetrodotoxin, a poison hundreds of times more potent than the chemical used to execute people in gas chambers. According to the Guardian, the fish get the toxin by feeding on poisonous sea creatures, such as snails and starfish, and concentrating the poison in the liver. Other parts of the fish — intestines, skin and ovaries, for example — can be poisonous, and the toxin can be transferred to benign parts.

Fugu-poisoned people first begin to feel numbness around their mouths. Paralysis follows, and then a painful death by asphyxiation. There is no known antidote.

Because of the delicacy’s potential to kill customers, chefs must train for at least three years before they can even take the fugu certification test. Still, there is no shortage of people willing to give the fish a swallow.

There’s a certain following of fugu foodies who enjoy the thrill of eating something potentially deadly. A meal of fugu sashimi served without a side of death can run upward of $300.

Between 2006 and 2015, 10 people died after eating the fish, the Guardian reported. Most of them were thrifty diners who attempted to prepare fugu themselves. In 2006, a 35-year-old woman dining at Fugu Fukuji, a Michelin two-star restaurant in Tokyo, nearly died after demanding to be served fugu liver, according to the Daily Mail.

Shortly after eating it, the woman said she had a headache and numb lips. She was rushed to a hospital and recovered. The Japanese government stripped the chef of his license.

But death-by-poison-fugu is so bizarre that occurrences of it have insinuated themselves into pop culture.

In 1975, Bandō Mitsugorō VIII, a Japanese Kabuki actor, ate four fugu livers after convincing a sushi chef that he had developed a method that rendered him immune to the fatal effects. It didn’t work.

And Homer Simpson famously dealt with his mortality after he believed he ingested fugu in an episode of “The Simpsons.”

That doesn’t mean that every blowfish is a floating poison factory. There are more than 100 varieties, with varying abilities to kill.

In fact, according to the Associated Press, the grocery store at the center of the fish scare had been selling a nearly nontoxic version called blunthead blowfish for years, with no ill health effects.

Authorities were uncertain how that relatively nontoxic type of blowfish had gotten confused with the insta-kill variety. But according to Time, the five packages were sold with their livers — the deadliest parts — still in place.

By Tuesday, two packages of the blowfish had not been found, but authorities said no deaths had been reported either. The search is ongoing.

But one thing was clear, store managers told the AP: They are out of the blowfish business.

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