During past ice ages,Earth experienced periods of near-total freeze-over,known as “Snowball Earth.” The question of how life persisted through these harsh conditions has long puzzled scientists.

Now, a team of researchers has found a surprising variety of microorganisms thriving in small pools of melted ice in Antarctica. Their discovery suggests that similar ponds could have provided refuge for life during “Snowball Earth” events.

The Cryogenian Period, which occurred between 635 and 720 million years ago, saw average global temperatures plummet to -50 degrees Celsius (-58 Fahrenheit). The equator’s climate resembled that of modern-day Antarctica.

Despite these extreme conditions, life continued to evolve. According to Fatima husain,the lead author of a study published in Nature Communications,there is fossil evidence of complex life forms “before and after the Cryogenian in the fossil record.”

Husain, a graduate student at the Massachusetts Institute of Technology, told AFP that “There are multiple hypotheses regarding possible places life may have persisted.”

Some theories propose that life found refuge in open ocean patches, deep-sea hydrothermal vents, or beneath thick ice sheets. Another possibility is that the tiny melted ice pools near the equator served as havens.

these ponds could have been crucial oases for eukaryotes, complex organisms that eventually evolved into the multicellular life forms that dominate Earth today, including humans.

Could alien life be hiding in ponds?

Melted ice ponds can still be found in Antarctica today, along the edges of ice sheets.

In 2018, a New Zealand research team explored the McMurdo ice shelf in east Antarctica and found several of these pools, which are typically only a few meters wide and less than a meter deep.

The bottoms of these ponds are covered in mats of microbes that have accumulated over time, forming slimy layers.

“These mats can be a few centimetres thick, colourful, and they can be very clearly layered,” said Husain.

These mats are primarily composed of cyanobacteria, single-celled organisms known for their ability to survive in extreme conditions.

Though, researchers also discovered signs of eukaryotes, such as algae and microscopic animals, indicating a surprising level of diversity within these ponds.The amount of salt in each pond appeared to influence this diversity.

“No two ponds were alike,” Husain said. “We found diverse assemblages of eukaryotes from all the major groups in all the ponds studied.”

She added, “They demonstrate that these unique environments are capable of sheltering diverse assemblages of life, even in close proximity.”

“Studies of life within these special environments on Earth can help inform our understanding of potential habitable environments on icy worlds,including icy moons in our Solar System,”

This discovery has implications for the search for extraterrestrial life.

“Studies of life within these special environments on Earth can help inform our understanding of potential habitable environments on icy worlds,including icy moons in our Solar System,” Husain said.

Saturn’s moon Enceladus and jupiter’s Europa are covered in ice, and scientists increasingly beleive they could harbor simple life forms. Several space missions have been launched to investigate these possibilities.