After completing a two-month underwater expedition to Zealandia, the nearly sunken landmass beneath the South Pacific Ocean, scientists have announced the discovery of million-year-old fossils as well as the evidence of large-scale tectonic movements – revelations that could give us more insights into the lost region's history.

More than 30 scientists from different parts of the world took part in the underwater excursion and drilled into the ocean floor, about 1,219m (4,000ft) below the surface. They used an advanced research vessel to drill at six different sites across landmass and collected 2,438m (8,000ft) of sediment cores showing evidence of tectonic changes and geological processes that may have taken place over last 60-70 million years.

"The cores acted as time machines for us allowing us to reach further and further back in time, first seeing the ancient underwater avalanches then evidence of rocks forged from a fiery origin," wrote Stephen Pekar, one of the scientists who took part in the study, in a blog post. "One could imagine somewhere nearby on Zealandia laid mountains that belched fiery rocks and rolling smoke."

But that's not the only discovery giving insights into Zealandia. Scientists have also identified more than 8,000 fossils, something that allows them to study the creatures that roamed on the landmass before it sank as well as predict their living conditions.

"The discovery of microscopic shells of organisms that lived in warm shallow seas, and spores and pollen from land plants, reveal that the geography and climate of Zealandia was dramatically different in the past," said Professor Gerald Dickens of Rice University, who lead the expedition.

Zealandia, spanning nearly across five million square kilometers, is believed to have broken off from Australia and Antarctica around 80 million years ago. Over the years, the submerged landmass has variously been described as a microcontinent, a continental fragment, and a continent, with the debate still going on.

The latest discoveries, however, are expected to help researchers define whether Zealandia is a continent or not. Additionally, further studies of sediment cores could give more insights into the lost landmass, revealing how its climate changed over a period of millions of years.