When we were kids the enormous, vicious, terrifying Rodents of Unusual Size (R.O.U.S.) in The Princess Bride gave us more than a few sleepless nights. But eventually we learned they were merely fictional creatures that could never really hurt us. Or so we thought. Because their real-life equivalents are currently threatening to overrun California by spreading like giant rats who eat all our crops and poison our water.

We're asking for the public's help in reporting nutria sightings or signs. This invasive species poses a real threat to California's remaining wetlands, among other dangers: https://t.co/TSanTW4m5G pic.twitter.com/Aj0P6TydAW

— California Department of Fish and Wildlife (@CaliforniaDFW) February 8, 2018

In a story we came across at Fox’s affiliate KTVU in Oakland, California’s Department of Fish and Wildlife is asking the public’s help in stopping the outbreak of nutria, “large, semi-aquatic rodents that reach up to 2.5 feet in body length, 12-inch tail length, and 20 pounds in weight.” Don’t worry, they’re much worse than they sound. Oh wait, no, you should worry. Native to South America, the invasive species are a problem in some parts of the U.S., but they were thought to be completely eradicated in California in 1960. However, since last March as many as 20 of them were spotted across the San Joaquin Valley.

That might not sound like a lot, but one single female “can result in more than 200 offspring, which can disperse as far as 50 miles,” which would prove devastating for the state, since nutria “are destructive, wasteful feeders that destroy up to 10 times the vegetation they consume.” If not contained, these beaver-muskrat looking nightmares threaten wetlands, cause extreme soil erosion, and more, plus they can also “contaminate drinking supplies with parasites and diseases transmissible to humans, livestock and pets.”

While they likely will not attack you the way they did Westley in The Princess Bride, these Rodents of Unusual Size could do far more lasting damage. That’s why the Department of Fish and Wildlife is asking help in spotting them, so the infestation can be stopped before it gets out of control. Even without coming across one personally, here’s how you can tell if one has been nearby:

“Signs of presence typically include cut, emergent vegetation (e.g. cattails and bulrushes), with only the base portions eaten and the stems left floating. Nutria construct burrows with entrances typically below the water line, though changing water levels may reveal openings. Similar to other aquatic mammals, nutria often create runs, or paths in and out of the water or between aquatic sites. Nutria tracks have four visible front toes and, on their hind feet, webbing between four of five toes. Tracks are often accompanied by narrow tail drags.”

Another sign is locals sobbing and ranting about giant rats eating all their food and poisoning their water. That’s a really good sign. You can report your sighting through the department’s website , by e-mail at [email protected], or by calling (866) 440-9530.

How would you react if you saw one of these in person? Don’t be afraid to tell us the truth in the comments below.

Featured Image: Wildlife Facts

More fascinating critters!

• Watch a baby octopus hatch.
• Listen to an orca try to imitate human language.
• Meet birds that reportedly try to set fires.