It thawed out — and then it multiplied.

Scientists successfully revived a “zombie worm” that had been frozen for 24,000 years, revealing new insight into how life survives in the most unforgiving environments over extended periods of time.

According to a study published in the scientific journal Current Biology, researchers found that the microscopic organism — identified as a rotifer — is a small, multicellular animal commonly found in freshwater environments that is known for its unusual durability, FOX News reported. 

The “zombie worm” has been frozen deep within Siberian permafrost since the Late Pleistocene, which was considered to be the final epoch of the Ice Age, ending roughly 11,700 years ago.

Scientists believe the Yedoma formation — an ice-rich, organic-laden permafrost formed during the Ice Age — helped sustain the specimen in a stable, frozen state for tens of thousands of years.

Researchers carefully thawed out the rotifer under strictly controlled laboratory conditions and were left stunned when the multiple millennia-old rotifer resumed normal biological functions.

And more shockingly, it was able to reproduce again asexually, indicating that its cellular structures remained intact after tens of thousands of years on ice.

“Our report is the hardest proof as of today that multicellular animals could withstand tens of thousands of years in cryptobiosis, the state of almost completely arrested metabolism,” lead researcher Stas Malavin told the Indian Defence Review.

The phenomenon behind the rotifer’s survival is cryptobiosis — a state in which metabolic activity in organisms slows to almost nothing, allowing certain life forms to endure extreme conditions such as freezing temperatures, dehydration and oxygen deprivation.

While single-celled life forms or simpler structures have been revived from ice before, the revival of a multicellular organism marks a major breakthrough for scientists, as more complex life forms face greater challenges surviving freezing conditions and thawing without damage.

But the breakthrough comes with a stark warning — as permafrost melts, scientists fear ancient microbes could be released into the wild, raising urgent questions about the risks they may pose.

Despite their microscopic size, rotifers have complex biological features — including digestive systems and simple nervous structures — making their ability to survive long-term freezing especially remarkable.

Scientists believe the results may have a broader scientific impact, particularly in understanding how cells resist damage caused by freezing and radiation over time.

The discovery — the second in recent years after Russian scientists uncovered Arctic “zombie worms” in 2021 — could also shape research in fields like biotechnology and astrobiology, where scientists study how life might endure in extreme, or even extraterrestrial environments.

However, scientists caution that the findings do not suggest that larger organisms, such as mammals, could be revived after similar periods of freezing.

Higher life forms are far more complex than microscopic organisms — making them far more susceptible to drastic cellular damage during the freezing and thawing processes.

Still, the study pushes the known limits of life on Earth, raising new questions about how long organisms can remain viable under the right conditions and potentially reshaping how scientists think about survival in extreme environments.