An entire continent, now submerged beneath the Indian Ocean, has been discovered by geologists studying rocks on the African island of Mauritius. There, traces of the ancient continent have shown up in crystals that date to a time before when the supercontinent Gondwana was breaking up some 200 million years ago, reports Phys.org.

"We are studying the break-up process of the continents in order to understand the geological history of the planet," explained geologist Lewis Ashwal, lead author on the paper, about how they stumbled on the ancient continent.

The age-old crystals are made of zircon, an incredibly resilient mineral capable of surviving geological processes and one that's typically found in continental granites. Because of that resiliency, zircons make the perfect substance for studying ancient continents, but researchers didn't expect to find zircons this old on an island that's so young.

"Mauritius is an island, and there is no rock older than 9 million years old on the island," said Ashwal. "However, by studying the rocks on the island, we have found zircons that are as old as 3 billion years."

Ashwal and his team theorize that the ancient zircons must have spewed from volcanic eruptions on Mauritius, drawn up from lava that mixed with the crust from a lost continent underneath the island. Their work is published in the journal Nature Communications.

Traces of this mineral have been found here before

Interestingly, this isn't the first time ancient zircons have been found on Mauritius, which was also the only known home of the extinct dodo bird. A study done in 2013 found traces of the mineral in beach sand as well, but that study was widely disregarded given that those zircons could have arrived by wind, or even on the shoes of human visitors. But it now appears that that study was on to something after all.

The "lost" continent has been tentatively titled "Mauritia," and researchers think it may have been one among several splinters that branched off as the supercontinent Gondwanaland broke up.

"According to the new results, this break-up did not involve a simple splitting of the ancient super-continent of Gondwana, but rather, a complex splintering took place with fragments of continental crust of variable sizes left adrift within the evolving Indian Ocean basin," said Ashwal.

The remnants of Gondwanaland that exist today are the continents of Africa, South America, Antarctica, India and Australia collectively. And perhaps Mauritia, the sunken continent, can now be added to that list as well.