u/Temporary_Rule_9486

Maybe I should have reframed the question, since aliens devouring people is such a classic trope: Would we be actually edible for them?

This is a sci-fi fanfic, so don't get mad!

I’m a huge fan of John Carpenter’s The Thing and the Mystery Flesh Pit National Park creepypasta, so I decided to mash them together.

The movie never really explains where the Thing came from. We know it crashed in Antarctica eons ago, but the crash itself suggests it wasn't the one flying the ship: it was likely a parasite that sabotaged the crew. This implies it isn't naturally a space-faring species.

Here’s the backstory I came up with:

Billions of years ago on a distant planet, a new lifeform emerges, or perhaps a biological version of Grey-Goo from a "Dark Forest" style civilization lands there. Within months, the entire biosphere is assimilated. However, because the Thing only imitates and doesn't create a balanced ecosystem, the planet’s environment collapses.

Without photosynthesis or a stable atmosphere, the planet becomes a wasteland. The Thing, possessing only the collective animal instincts of what it consumed, senses its doom. It retreats to the deepest ocean trenches, merging into a massive, amorphous blob of flesh to survive. Eventually, the oceans boil away and the atmosphere vanishes, leaving the creature entombed under layers of chitin and dead tissue.

Fast forward billions of years: a future humanity (unaware of the ancient Antarctica incident) discovers this "dead" planet. They begin excavating the massive organic remains, unaware of the dangers.

Deep inside the core of the dead body, a few microscopic cells are still alive, waiting for a fresh host to start the cycle all over again.

So, the interesting take in this story is the idea of the thing being a biological weapon. It’s a specialized predator, but it has a fatal flaw: if it invades a world without intelligent life, it’s effectively stranded. Without a host to provide the technical knowledge needed to build or pilot a spacecraft, not to mention the biological blueprint for a working brain, the Thing is stuck on the planet it just conquered, doomed to wither away once the ecosystem collapses.

Unlike coal, which formed from lignin-rich land plants, most of Earth’s petroleum originated from marine microorganisms. The oldest bitumen deposits date back to an era of purely microbial life, leading scientists to believe these ancient reservoirs resulted from the compression of ancient microbial mats on prehistoric seafloors.

Since complex multicellular life is likely far rarer than microbial life in the cosmos, any hydrocarbons discovered on alien worlds would most likely share a similar microbial origin. Even on a barren, geologically dead planet, these oil and bitumen deposits could remain trapped and viable for extraction even billions of years after surface life has gone extinct.

While there are more practical ways to harvest hydrocarbons in space, such as tapping the methane-rich moons like Titan, I think the idea of "fossil fuels" on alien worlds is rather interesting for sci-fi.

Even if we do not consider oil, there are many fossil resources that were instrumental in the development of modern societies. The richest iron ore deposits, for instance, date back to the Great Oxidation Event, a process driven by the accumulation of oxygen produced by cyanobacteria. While coal is a well-known fossil resource, there are others, such as phosphorites, which formed from the accumulation of organic debris on the seafloor, including the bones, teeth, scales, and fecal pellets of ancient marine organisms.

Even the chert and flint used by prehistoric humans have biological origins: they are composed of microcrystalline silica derived from the glassy skeletons of radiolarians (zooplankton) and diatoms (algae). When these organisms died, their shells formed a silica-rich ooze on the ocean floor that eventually hardened into rock.

More recent examples include peat, which serves as a precursor to coal and has been used traditionally to heat homes in Britain.

The fundamental takeaway is that even if life has gone extinct on an alien planet by the time we arrive, that life may have left behind a legacy of concentrated, valuable resources that could prove essential for human colonization.