THEY’ve been in suspended animation for 42,000 years. But they never died.

Nematodes.

They’re microscopic roundworms — no more than 1mm in length — that thrive in soil.

They’re a critical component of any ecological system.

These have not been active since the Pleistocene — an age of mammoths, marsupial lions and giant sloths

The May edition of Doklady Biological Sciences reports two species of nematodes have been revived — the first ever evidence that such a thing was possible for multicellular life.

Nematodes are not normal critters, though.

Some can be found thriving up to 1.3km beneath the Earth’s surface.

They’re also very adaptive.

In this case, Russian scientists recovered a sample of nematodes preserved in a frozen squirrel burrow in the Alazeya River region of Yakutia, Russia. It was abandoned some 32,000 years ago. Another sample was taken from the Kolyma River region of Siberia. It was dated to 42,000 years ago.

They were transported in temperature-controlled Petri dishes and taken to a laboratory. The nematodes were separated from the soil, and gently defrosted over the course of several weeks.

Then, the researchers saw them moving and eating.

According to the study, it’s the first evidence of “natural cryopreservation” of multicellular life.

“It is obvious that this ability suggests that the Pleistocene nematodes have some adaptive mechanisms that may be of scientific and practical importance for the related fields of science, such as cryomedicine, cryobiology, and astrobiology,” the study reads.

The Pleistocene was an era which endured many ice ages between 2.6millioni and 11,700 years ago.

And it’s not the first time something that old has been brought back to life.

A 30,000-year-old giant virus found in Siberia’s permafrost also reanimated after being thawed.