We’ve said it before and we’ll say it again: pound for pound, weasels are some of the most tenacious animals on the planet. In nature, they routinely take on opponents 10 times their size. In mythology, they crawl up monsters’ butts and destroy them from within. And in Europe, a weasel may have just taken out the largest machine in the world.

The Large Hadron Collider, or LHC, is one of the most exciting things to happen in science in the last 50 years. The $7 billion particle accelerator is a masterpiece of international collaboration, cached in a massive tunnel 300 feet under the French-Swiss border. It’s here that physicists hope to unravel the secrets of atomic particles, and thus the very material of our universe. It’s a lofty, futuristic goal, but it might be attainable—if they can only keep nature from mucking it up.

"We are in the countryside, and of course we have wild animals everywhere," CERN head of press Arnaud Marsollier told NPR. In 2009, shortly after construction of the LHC was complete, a bird passing overhead dropped a hunk of bread onto some exposed machinery aboveground, causing the machine to overheat. The LHC hadn’t been turned on yet, but if it had, that baguette would have shut it down.

Yes, the LHC is super-high-tech, but it’s also enormous, and therefore has a lot of vulnerable points. When the machine shut off last night, alarmed staff started looking for the source of the issue, and they found it: tiny teeth marks in a power cord, accompanied by the electrocuted body of a very small animal. The remains have not yet been examined, but Marsollier told NPR the culprit was “a weasel, probably.”

The least weasel (Mustela nivalis) that stalks the region is ferocious, adorable, and always ready for a fight. The little carnivore’s metabolism is so rapid that it’s in constant need of food, which means constant killing, which can mean entering fights in which the odds are most definitely not in its favor.

In other words, if we had to nominate an animal Most Likely to Attack the LHC, we’d go for the weasel.