Every now and then, the Internet "discovers" something you just sort of assumed everyone knew.

Like, for example, that pufferfish inflate themselves with water and not air. It seems logical that people would assume that fish – which famously remain underwater when they are not dead – fill up with water when they inflate themselves.

But apparently vast swathes of the Internet learned their information on pufferfish from the underwater levels in Super Mario.

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But the latest "discovery" is one I'll admit I wasn't expecting. For some reason, I saw a koala and assumed "the adorable teddy bear definitely makes some sort of light squeaking sound at all times" and thought nothing further of it.

Well, I was wrong. And I'm guessing the sound you're imagining is also wrong. Brace yourselves.

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People have mixed feelings.

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Koalas actually let out a range of noises, including high-pitched squeaking crying sounds as demonstrated by this poor koala when it was kicked out of its tree.

Sidebar: If you're worried about the poor little thing, it won the tree back in the end.

"This poor little Koala is trying to stake out it's own territory when it is kicked out of the tree by a big bully," Koalafication wrote on YouTube. "Persistence pays off as this brave young Koala claimed the tree all to himself by nightfall."

The sound they're making in the viral video (a sort of pig crossed with a snoring man crossed with a motorbike) is the mating call of a male koala.

"Koalas might look cute, but they can produce bellowing sounds during mating season that have been compared to a donkey braying and a frog vomiting! Keepers caught our new male, ‘Storm’ [in the video below], in full voice this week," Taronga Zoo Sydney explained on YouTube.

"Research suggests male koalas like Storm let out these distinct calls to attract females and avoid confrontation with competitors."

So there you have it, he doesn't always sound like that, he was just horny.

Now, as a palate cleanser, please enjoy this video of a porcupine enjoying some corn and letting out the most adorable sound since records began.