Tim Henderson, a “flusher” or trunk sewer technician holds a “fatberg” specimen as he works in the Regent Street and Victoria sewer in London in December 2014. (Adrian Dennis/AFP/Getty Images)

A massive “fatberg” weighing nearly as much as a school bus has been removed from a London sewer.

Never heard of a “fatberg?” You’re going to be so glad you asked.

It’s a blob-like, toxic lump of waste that forms when cooking oil and other fats wind up in pipes. The oil congeals and clumps with other household waste, blocking sewers and grossing out the Thames Water officials who have to deal with it.

This one was so large that it broke the roughly 70-year-old sewer where it was discovered. Repairs are expected to take two months and cost about $600,000, the Guardian reported.

“We see blockages all the time on household sewer pipes, which are about big enough for a cricket ball to pass through, but to have this much damage on a sewer almost a meter in diameter is mind-boggling,” Thames Water repair and maintenance supervisor Stephen Hunt told the Guardian.

Hunt, who has been overseeing the fatberg’s removal, added that the utility company will have to replace large expanses of the sewer — nearly 100 feet of pipe in total.

Fatbergs seem to be an unfortunately common occurrence in London — a search of the term on Thames Water’s Web site turns up a dozen news releases from the past four years. In August 2013, the utility company removed what it said was the largest fatberg in British history — a 15-ton behemoth of  “wrongly flushed festering food fat mixed with wet wipes,” CBS reported.

That fall, the utility company even formed a “fatberg hit squad” to tackle the problem.

“The sewers serve an important purpose, they are not an abyss for household rubbish. Fat goes down the drain easily enough, but when it hits the cold sewers, it hardens into disgusting ‘fatbergs’ that block pipes,” Rob Smith, Thames Water’s chief sewer flusher and a member of the fatberg hit squad, said in a statement about the new agency.

The “fatberg” phenomenon happens elsewhere too, though no other city has given it such a dubiously affectionate nickname. In New York City, clearing backups caused by grease cost an estimated $4.65 million in 2013.

In both New York and London, utility companies say the large numbers of restaurants are responsible for large amounts of grease that get flushed into sewers. Wet wipes — which are marketed as flushable but don’t disintegrate in the sewage system — exacerbate the issue.

For those who want to avoid being part of the problem, Smith, of Thames Water, has this advice:

“We want everyone to remember the sewerman’s war cry: Bin it, don’t block it.”