Earlier this year, scientists suggested the presence of a large underwater mass known as Zealandia, which sunk beneath the waves tens of millions of years ago but was, when it was at sea level, very large indeed.

A nine-week voyage to the seafloor off New Zealand and Australia revealed evidence of land-based fossils on the submerged landmass, which is now more than 3,200 feet below the surface. As well, the expedition found that Zealandia's crust was not as deep as the surrounding oceanic crust, confirming the theory that the land was once much higher up.

Working aboard a ship called the JOIDES Resolution, the scientists drilled more than 8,000 feet below the surface, at six sites at various points along the Zealandia landmass. What they discovered included remains of pollen from land plants and remains of organisms whose home is in warm shallow seas.

Zealandia encompasses nearly 2 million square miles of land, about two-thirds the size of Australia, but only 6 percent of Zealandia is above sea level. Among that 6 percent are New Zealand, New Caledonia, Norfolk Island, and several other smaller islands.

Australia, Antarctica, New Zealand, and Zealandia were all part of the megacontinent Gondwanaland, which broke up 180 million years ago. New Zealand broke way about 85 million years ago, and Zealandia sunk some time after that.