You'd think we'd know all there is to know about planet Earth by now, but scientists are constantly surprising us with new discoveries.
Think there are only seven continents? Wrong, researchers have found another one largely hidden beneath the ocean.
Once you've wrapped your head around that, you might like to know that the Earth is starting to spin faster and the Moon is slowly drifting away from us into space.
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And in recent years, boffins have got some more fact bombs for us about exactly what's beneath our feet.
If you cast your mind back to school science lessons, you'll remember that the planet is made up off a relatively thin outer crust, a mostly solid mantle which makes up 84 percent of the planet's volume, and a super-hot molten outer core and a solid inner core.
Well, prepare to throw that out of the window, as in recent years scientists have made some surprising discoveries.
Scientists think that, at some point, something strange happened inside the Earth's inner core.
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Seismologists at the Australian National University believe the change occurred after a ‘significant global event from the past’.
Through their studies in specific earthquakes and monitoring 'seismic waves reverberating through the entire planet', Thanh-Son Phạm and Hrvoje Tkalčić spotted new details about the core which hadn’t been noticed before.
In short, they found the 'innermost inner core' was slightly different to the rest of the inner core, and was in fact a giant metal ball about 400 miles wide.
Thanh-Son Phạm told The Washington Post: “Clearly, the innermost inner core has something different from the outer layer."
So despite the core being made of the same materials as the rest of the inner core, this metal innermost core may have different properties, the scientist explained.
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He said: “We think that the way the atoms are [packed] in these two regions are slightly different.”
He went on to add that this means seismic waves travel through it at a different rate.
But that’s not all, researchers also believe that this solid metal core could be a key component to understanding how life evolved on planet earth and the theory of evolution.
Due to their study, they believe that the metal inner core could be a ‘fossilised record’ of a significant tectonic event a few hundred million years back, with the core changing its composition shortly afterwards.
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The researchers wrote in The Conversation: “Studying Earth’s center is not just a topic of academic curiosity, but something that sheds light on the very evolution of life on our planet’s surface."
You really do learn something new every day.
Topics: News, Science, World News, Space