BBC: More than 750 million years ago, most or all of Earth’s land consisted of a single supercontinent now called Rodinia. As Rodinia gradually fragmented to form the separate continents that exist today, some bits may have broken off and sunk over time. From studying grains of sand on Mauritius, researchers found that while the sand grains dated back to a volcanic eruption 9 million years ago, there were also zircons that dated back as far as 600 million years ago. Trond Torsvik from the University of Oslo in Norway and colleagues explain in a paper published in Nature Geoscience that they believe the zircons were dragged up to the surface of Mauritius from one of those fragments of ancient continent during a volcanic eruption. Torsvik says further research in the form of seismic imaging or drilling is needed to find any still-existing early continental fragments.