Earth isn't the steadfast planet we assume it to be. Its continent-size slabs constantly move, buckle, and vanish beneath each other over the millennia, all while hardly leaving a trace.
But geologist Roi Granot, a senior lecturer at Ben Gurion University in Israel, says he's discovered the most ancient slab of seafloor on Earth to date.
The roughly 60,000-square-mile piece of crust has been hiding below the eastern Mediterranean Sea for about 340 million years (give or take 30 million years).
That means it's from right around when Earth's landmasses came together to form the supercontinent Pangea, which later separated into the continents we recognize today.
It's also about 70% older than any other seafloors researchers know of, including those of the Atlantic and Indian oceans.
What's more, Granot thinks the ancient slab might be a remnant of Earth's long-lost Tethys Sea (or Ocean).
"[W]e don't have intact oceanic crust that old … It would mean that this ocean was formed while Pangea, the last supercontinent, was still in the making," Granot wrote in an email to Business Insider.