Around 3 billion years ago, Earth may have been covered in water – a proverbial "waterworld" – without any continents separating the oceans.

That's according to a new study published Tuesday in the peer-reviewed scientific journal Nature Geoscience by a pair of researchers from the University of Colorado-Boulder and Iowa State University. They uncovered an ancient piece of marine sediment in the Western Australian outback that may have some answers for the evolution of life on Earth.

Benjamin W. Johnson, an assistant professor of geological and atmospheric sciences at Iowa State, worked in conjunction with Boswell Wing at the University of Colorado to examine a nearly 3.2-billion-year-old piece of oceanic crust.

Johnson told USA TODAY that one of the biggest suggestions of the research is that "without significant continental crust above sea level," the ocean would be the only place where early life existed.

The crust, found in the Panorama district of the Pilbara Craton, provides a clear "isotope archive" for the ocean – or history of the different variants of a specific element in the ocean.

What that means, according to the researchers, is that the composition of the water at the time contained more oxygen-18 than oxygen-16, the latter of which is more common in the modern ocean and is a slightly lighter isotope.

The most plausible explanation for that is as the continents formed, the land ended up "sequestering" oxygen-18 from the oceans.

This doesn't mean there was no land on Earth, Johnson said. Wing explains it as if Earth was like the Galapagos Islands "from the West," with vast expanses of ocean and tiny islands dotting the ocean.

"Our work doesn't mean there was zero dry land, just that it must have been much, much smaller in extent than today, with only small island chains emergent above the ocean," Johnson told USA TODAY.

It may also prove the possibility that other, water-heavy planets outside the galaxy could evolve into what Earth looks like now.

"If the Earth was a waterworld for the first quarter or so of its history, then perhaps other Earth-like planets elsewhere in the galaxy would undergo a similar evolution," he said.

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