Longest animal cryobiosis
Panagrolaimus aff. detritophagus, Plectus aff. parvus
42,400 year(s)
Russian Federation ()

As reported in the journal Doklady Biological Sciences in May 2018, two species of nematode (roundworm) – Panagrolaimus aff. detritophagus and Plectus aff. parvus – frozen in Arctic permafrost soil that was radio-carbon-dated to somewhere in the region of 41,000–42,400 years old were reanimated after several weeks' cultivation in a lab. The nematodes were collected in 2015 from near the Alazeya River in the Siberian region of Yakutia, north-eastern Russia, and are presumed to be of a contemporaneous age to the soil where they were found.

Also discussed in the study, the same two nematodes were reanimated from permafrost taken from the Duvanny Yar outcrop in the lower reaches of the Kolyma River in north-eastern Siberia in 2002; this soil sample was dated to around 32,000 years old.

The research was a collaboration between Moscow State University, the Russian Academy of Sciences, the Higher School of Economics (all Russia) and Princeton University (USA).