Inside part of the Large Hadron Collider. (Photo: Image Editor/CC BY 2.0)

Located in the countryside near Geneva, Switzerland, the Large Hadron Collider (LHC), the world’s most powerful and expensive particle accelerator, does important work for physics, recreating events that happened right after the Big Bang by smashing high-energy particles into one another at super-fast speeds. 

But all that stopped early Friday, when a mysterious power outage halted the 38,000-ton machine; engineers who investigated found that even the smaller creatures among us can threaten the work of dedicated scientists—specifically, a tiny weasel.

The little mammal reportedly snuck into the collider’s electrical system and gnawed through some very important wires, causing a short circuit that damaged the collider’s transformer connections. According to the BBC, the creature didn’t survive the escapade. 

Weasels and their ilk love to chew and explore. Unfortunately for the scientific community, this weasel chose its last great adventure just as LHC scientists were closing in on new data for new particles and the Higgs Boson, a theorized particle that can help explain a lot of modern particle physics, according to NPR. The physicists will have to wait; the LHC will shut down for a week or two to fix damages. 

For officials at the LHC, this isn’t necessarily an unexpected occurrence in the wilds of Switzerland. In 2009, for example, a bird is suspected of dropping a piece of bread into the machine, causing a brief stoppage then. 

“We are in the countryside, and of course we have wild animals everywhere.”Arnaud Marsollier, representative for CERN, the organization of scientists who run the LHC, told NPR. 

While CERN’s own thorough report on the incident says it plans to “resume physics” as soon as repairs are made, it also shares that this is, “Not the best week for LHC!”Apparently, it’s not the best week for small adventurous mammals, either.

Update, 5/2: An earlier version of this story incorrectly stated that weasels were rodents. We regret the error.