I have devised an alien species for a universe I am working on. They originate from the same planet as my high-pressure creatures (What would happen to a high-pressure creature in a low-pressure atmosphere (50atm)?), but can survive comfortably in a much broader range of environments due to their robust nature (they have survived nearly every mass extinction that the planet has to throw at them and can even survive for extended periods of time submerged in boiling water, freezing water or exposed to the vacuum of space. Think of them as being a little like tardigrades).

Although they did evolve on this particular planet they have since been transported around the universe and are currently taking up residence inside of ships and space stations that are made of metal.

The idea behind them is that they are essentially a pest species - not dangerous to any organic life form, but making their living eating away at the hulls of such ships and stations, often causing massive damage and even hull bursts.

They possess a tough exoskeleton made of aragonite (like a chiton) and bear a vague resemblance to some kind of arachnid or crustacean. Is such a creature possible? Can any biological organism (carbon-based or otherwise) survive by chewing up metal, and metal alone?


There are many kinds of bacteria that damage iron as they grow by producing various kinds of acid, such as sulfuric acid, as waste. At least one kind of chemoautotroph, ferrobacillus ferrooxidans, actually uses the oxidization (rusting) of inorganic iron as a primary energy source. So yes, an organism that eats metal is certainly possible.

As you might imagine, there isn't a whole lot of energy to be gained by rusting iron, so I wouldn't expect to see high-energy organisms (animals) chowing down on metal. A contagious, corrosive mold would certainly be a threat to space travelers though, and isn't that far-fetched.

If you want to have the creatures be arachnid-like, perhaps there could be a form of symbiosis, where the animal 'farms' the iron-eating mold by spreading its spores, goes into hibernation for a while, and then harvests the mold after it has spread.


energy is not the only reason to eat stuff. Metal may be a bad energy source but it makes a decent building material.

at the crudest you could have creatures that just break up the metal to make homes, similar to a caddisfly larvae making cases or a paper wasp making its nest.

you could also have something mollusc or crustacean like that consumes the metal to make its shell/exoskeleton


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