A quick search reveals Halicephalobus mephisto which was

detected in ore recovered from deep rock fracture water in several gold mines in South Africa [...] 3.6 km (2.2 mi) under the surface of the Earth.

Have any deeper living organisms ever been found?

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    $\begingroup$ I suspect the answer to this question is the same as to the answer as to how deep underground we've ever actually looked for living organisms. $\endgroup$ Commented Jul 14, 2022 at 18:27
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    $\begingroup$ Halicephalobus mephisto, the "devil worm" (actually a nematode) was, as of 2017, the deepest discovered species -- found living at 3.6 km below the surface! However, this species ties another deep species: Plectus aquatilis found a number of years before (~2011 I think; don't quote me). I know of no recent updates regarding multicellular organisms. Looks like acvill's answer covers fairly recent (2021) "deepest" cellular evidence $\endgroup$ Commented Jul 15, 2022 at 14:38

1 Answer 1


Have any deeper living organisms ever been found?

In 2021, researchers recovered microbial cells and DNA from rocks retrieved from a depth of 4,850 m below the surface.1 The New Scientist covered this finding in an article titled "Deepest land microbes ever found".

Dong and Huang say that, to the best of their knowledge, these are the deepest known microbes ever found on land. Demonstrating that the cells are living will be a challenge as microbes that live deep below the surface often operate on such a slow timescale that they show few typical signs of life such as movement or reproduction.

But there are reasons to suspect the microbes may be alive. Most importantly, they are intact rather than just cell fragments, which might hint they are carrying out basic cellular repair.

  1. Dai X, Wang Y, Luo L, Pfiffner SM, Li G, Dong Z, Xu Z, Dong H, Huang L. Detection of the deep biosphere in metamorphic rocks from the Chinese continental scientific drilling. Geobiology. 2021 May;19(3):278-291.

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