For everyone who found this interesting, the research paper it originally came from us Bar-On et al (2018) and it's free to read here:
@Nausicaa Deep below the ground. Shallow subsurface is where you find plant roots and fungus. Deep subsurface is below that. There's a lot going on in the deeper parts of Earth's crust.
FR : Ceci est une instance queer, qui vise à être aussi confortable et safe que possible. Nouvelleaux élèves bienvenu'es !