I read as a child the lurid pulp fantasies of Edgar Rice Burroughs, and similar authors that conjured vivid hallucinations of cavernous worlds subterranean. Mere reality cannot compete LOL.
The ability of living things to habituate to environments on Earth is astounding. Microbial species live kilometers deep in suboceanic rock, feeding on the sparse resources that percolate therein. While microbes in active ecosystems can reproduce every ~20 minutes, deep in the lithosphere they can only reproduce once in a century.
Archaia is yet remnant in such places.