4.4 billion-year-old chunk of Earth oldest to ever be discovered

A 4.4 billion-year-old chunk of Earth is thought to be the oldest physical geological proof of how long our planet has been around - and how long it's been habitable.

For context, Earth itself is 4.54 billion years old, so this discovery is almost as old as its existence - although it's still not the oldest object ever found (that award goes to some interstellar dust).

The 'chunk' is a super blue speck of zircon found out in Western Australia's Jack Hills, however, don't get your cameras out just yet, as the piece in question is at a microscopic level.

Zircons are a gemstone created from zirconium, and while they can come in any bright colour, blue is one of its most common forms. Known for its flashes of light when moved, it can often be confused with cubic zirconia, which is a manmade alternative known for its use in jewellery.

University of Wisconsin-Madison

They're also one of the oldest geological discoveries on the planet, and can help geologists and scientists tell more about the Earth's history.

“This confirms our view of how the Earth cooled and became habitable. This may also help us understand how other habitable planets would form," Professor John Valley, a geochemist at the University of Wisconsin-Madison, said in a statement made in 2014.

"The Earth was assembled from a lot of heterogeneous material from the solar system,” added Valley. “Our samples formed after the magma oceans cooled and prove that these events were very early."

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