Although the name is a bit of a mouthful (not literally!
...oh dear) it is, on closer inspection, a retrofitted acronym
. Yes, this sort of thing does
amuse academics! :)
Anyway, the essential word here is lithoautotrophic - which means 'gets all its energy from rocks'. So these kinds of microbes can live on rocks and gasses, deep underground. For example, samples taken from 1,000 meters down have shown activity when grown in a solution of dissolved rock (basalt). The rock generates hydrogen, which can be used by the microorganisms as food.
The extreme environment of the deep subsurface (where temperatures can be 70°C and more) is an unlikely place for any life form. However, it appears that life has extended even here. I use the word extended advisedly, since some have suggested that mars might have similar SLiME's in its crust. However, the prescence of life in an inhospitable environment does not imply that it could have originated there. Unless mars used to have abundant life, and SLiMEs are all that is left, it seems unlikely.
Information from :
The Spark of Life by Christopher Wills & Jeffrey Bada OUP