From LEGO bricks to unexploded World War II bombs, some very weird (and occasionally dangerous) things have washed up onto waterfronts around the globe. Few of them, however, have had the “ick” factor of fatbergs—large, toxic fat blobs that are sliming their way onto the UK’s shoreline, posing a threat to beach-goers and their pets as temperatures get warmer, the Daily Mail reports.

Fatbergs are solid blobs of congealed fat, oil, or grease. (Fittingly, the name “fatberg” is a combination of “fat” and “iceberg.”) They form in sewers when people dump cooking byproducts down drains, or in oceans when ships legally release sticky waste products like palm oil. Often, a fatberg’s sticky surface will attract other floating trash items, like wet wipes, diapers, condoms, or even syringes. The final product? A giant, germ-covered hunk of lard and garbage that’s harmful to anyone (or anything) that comes near it.

According to the Mirror, the boulder-sized fatbergs of congealed palm oil have drifted over to British beaches from the Caribbean. Lately, the lumps have been spotted in east Sussex and Kent. In the past, they’ve come ashore in pl aces like Cornwall, Devon, and Hampshire.

Officials have warned locals to stay away from the stinky blobs, which look like candle wax and have been described as smelling like “the worst wet dog you’ve ever encountered.” Not only are fatbergs likely covered in bacteria, there’s a risk that pet canines—which might be attracted to the smell of palm oil—will try to taste them. Since the oil is gelatinous, it might get stuck in the esophagus and require surgical removal. In 2014, the Daily Mail writes that several dogs died—and dozens got sick—after nibbling on similar palm oil fatbergs.

Officials are putting up signs on beaches to warn pedestrians of potential fatbergs. In the meantime, what should you do if you encounter one of the blobs? The Cornish Guardian shared advice from a local council spokesman: "We'd suggest keeping children and pets away from the deposits," the councilman said. "And if you come into contact with the substance, wash it off with soap or shower gel and wash your clothes."

While fatbergs are currently threatening the UK's shores, the toxic lumps are perhaps most notorious for mucking up city sewers around the world. In 2013, a 15-ton fatberg about the size of a school bus was removed from London’s sewers. And last February, a crane was required to pull a giant fatberg made of sludge and wet wipes out of a sewer pipe in New South Wales, Australia.

To learn more about what fatbergs are—and why they're bad news—watch the above video, courtesy of BBC News.

[h/t Daily Mail]

All images courtesy of iStock