And from the buried fruit tissues, a team of Russian scientists say, they have managed to resurrect an entire plant in a pioneering experiment paving the way for the revival of other species.
The Silene stenophylla is said to be the oldest plant ever regenerated - and it is fertile, producing white flowers and viable seeds.
The experiment proves permafrost serves as a natural depository for ancient life forms, say the researchers, who published their findings in Tuesday's issue of Proceedings of the National Academy of Sciences of the United States.
Svetlana Yashina of the Institute of Cell Biophysics of the Russian Academy Of Sciences, who led the regeneration effort, says the revived plant looks very similar to its modern version, which still grows in the same area in northeastern Siberia.
"It's a very viable plant, and it adapts really well," she told The Associated Press in a telephone interview from the Russian town of Pushchino where her lab is located.
She voiced hope the team could continue its work and regenerate more plant species.
The Russian research team recovered the fruit after investigating dozens of fossil burrows hidden in ice deposits on the right bank of the lower Kolyma River in northeastern Siberia, the sediments dating back 30,000-32,000 years.
The sediments were firmly cemented together and often totally filled with ice, creating a natural freezing chamber fully isolated from the surface.
"The squirrels dug the frozen ground to build their burrows, which are about the size of a soccer ball, putting in hay first and then animal fur for a perfect storage chamber," says Stanislav Gubin, one of the authors of the study. "It's a natural cryobank."
The burrows were located 38 metres below the present surface in layers containing bones of large mammals, such as mammoth, wooly rhinoceros, bison, horse and deer.
Gubin says the study demonstrates that tissue can survive ice conservation for tens of thousands of years, opening the way to the possible resurrection of Ice Age mammals.
"If we are lucky, we can find some frozen squirrel tissue," Gubin told the AP. "And this path could lead us all the way to mammoth."
