It is fermented fish, a Scandinavian delicacy. Surströmming is supposed to be opened outdoors in a barrel of water to contain the stench, not indoors. Never, never, indoors! In an enclosed space, the smell is like the fetid breath of Hell, even worse than fat-people smell, and it clings permanently to everything.This is quite literally a taste that does not travel, because the fermentation releases gases that puts the tins under high pressure, making them liable to explode while being transported.

https://visitsweden.com/what-to-do/food-drink/food/swedish-kitchen/fermented-herring/

you can see most of them as is.

i don't know. i do know that this stuff has to be handled differently and gutted and cleaned before eaten. then slapped in a sandwich. but if something ferments in a can and causes a person to rear back in revolt, it's won't be on my menu.

there's this other horrendously gross food item called durian fruit. why?