Black mambas are highly venomous snakes native to Africa. They have a potent venom and are one of the deadliest snakes in Africa. A bite has a fatality rate of 100 percent if left untreated.

In a Facebook post here, snake catcher Nick Evans—who provides a snake removal service in province South Africa’s KwaZulu-Natal province—said he was called to deal with a snake at a house in the greater Durban area on Tuesday evening.

He assumed the call was about a house snake. But Evans found an 8.5ft, highly venomous black mamba curled up next to the TV behind some boards. The snakes are among Africa’s longest, and can grow up up 14 feet in length, though their average length is around 8 feet.

The man had been sitting down watching TV after a long day’s work, when the huge snake slithered through the sliding door next to him, Evans said. “I can only imagine his reaction,” he said.

The mamba did not lash out and attack the man, according to Evans, and instead “went about its business.”

Black mambas are shy and usually avoid humans. Evans urges local people not to kill black mambas if they see one, as they only tend to bite if threatened or scared.

Evans said it was a “quick and easy” catch. The black mamba was then released in a safer environment away from people.

Evans said this call was one of the “most rewarding” he has had, as people at the unnamed premises used to kill mambas. Evans said he urged them “repeatedly” not to kill the snakes, partly because of the danger they pose. He also wanted to resolve the issue “more peacefully.”

“I am so, so grateful to the resident’s neighbor for phoning me, and to all of them for not killing it,” he said.

It is not uncommon for people in Durban to find black mambas lurking around the home, Evans told Newsweek.

Black Mambas are generally found in properties bordering valleys or nature reserves, which are the perfect habitat for the snakes. Evans said he has found them nearly everywhere in the home, including gardens, sheds, ceilings, living rooms, bedrooms and bathrooms.

People can accidentally create a perfect black mamba habitat around their home by being messy, Evans said.

Piles of rubbish and wood, as well as untidy storerooms and sheds, can create a warm, safe hiding place for mambas.

Houses might also attract prey including rats, and feral cats; black mambas have been known to feed on their kittens.