I'm currently writing a story in the universe of the role playing game "Mahamot".

Basically, in this world, what's left of human kind lives on huge spaceships swarming with little plants called "micelis" (it seems to be a French game, so I don't have any translation for this word which doesn't even exist in French). The description of those micelis is unclear but they are mostly a mix of mosses and lichens and their size ranges from one micron to ten centimetres. There are several thousands species of micelis and they are the base materials for everything humans need (clothes, food, weapons...).

Now here is the rub : in this game, swords, axes, knives and so on are said to be made of a something that closely resembles metal. So how can people turn mosses and lichens into such weapons ?

Two problems :

  • A plant doesn't seem to be hard enough to forge a weapon. So micelis have to be transformed in a way that reinforces their structure. That being said, micelis aren't precisely described so if you can imagine how can some species naturally came to become stiff and hard, that'd be great !
  • Since micelis are ten centimetres long at best, you have to use several of them to forge a weapon. But how can you mix them together into one object that won't break each time you hit something ?

Feel free to invent micelis species and features that would allow them to be turned into weapons more easily. As long as those features are plausible for a plant and respect the few indications I gave about micelis, it's OK with me.

Remember that everything you use to turn micelis into weapons is also made of micelis. In particular, I only have access to chemicals that can be created by plants.

Last thing you should know : there is absolutely NO magic in this world.

  • $\begingroup$ What about polymer/composites? They are extremely NOT metal like (a polymer composite would not be plastic like a metal would be, and would be much much harder, throw in some hydrogen bonds and it might even be dense enough), but can make great weapons (swords, axes etc). $\endgroup$
    – Aron
    Apr 19, 2016 at 7:58
  • 1
    $\begingroup$ maybe your "micelis" is somehow derived from mycelium, the fiber-like parts of fungi? $\endgroup$
    – Burki
    Apr 19, 2016 at 14:28
  • $\begingroup$ Wooden swords &c can be quite effective: see for instance the account of Miyamoto Musashi's duel with Sasaki Kojirō, or look up 'bokken'. Or try working with e.g. mountain mahogany. Then there are hard/sharp bio-composites like shells, corals, &c. $\endgroup$
    – jamesqf
    Apr 19, 2016 at 17:35
  • $\begingroup$ @jamesqf The problem is there are no trees on the spaceships. Some micelis might have wooden sections, but only centimetres long. $\endgroup$
    – Rebouh
    Apr 20, 2016 at 11:54
  • $\begingroup$ @Burki I hadn't thought of that, but it's very likely ! $\endgroup$
    – Rebouh
    Apr 20, 2016 at 11:55

4 Answers 4


A few things exist in nature which "produce" metals - Delftia acidovorans can accumulate deposits of gold and/or iron (1), while other bacteria (Thiobacillus ferrooxidans and Leptospirillum ferrooxidans) are capable of accumulating rusty iron deposits in iron-rich water (2).

Perhaps the mosses and lichen are accumulating metal (or else have a symbiotic relationship with bacteria that accumulates metal) and their harvesting and processing can produce an alloy, once the organic material is burnt or catalyzed off.

That highlights one key difference, though:

...swords, axes, knives and so on are said to be made of a something that closely resembles metal. So how can people turn mosses and lichens into such weapons ? [Emphasis mine.]

If they aren't actually useful because they accumulate metal, that's something else entirely.

So a couple possibilities occur to me, here.

Maybe the reason these finished byproducts 'resemble' metal is because they are not pure examples thereof - more like brittle, or spongey, alloys of silica, iron, copper, and what-have-you that they can metabolize from the walls of spaceships.

Mixing them together into one object that isn't too fragile would be a matter of smelting them, refining them (by skimming off impurities, for instance), or even growing them together in an organic (still-living?) matrix. Perhaps the matrix is formed from 3D printed silica or silicone, or carbon fibers. It's hard to say what technology is available, based on your description.

It's also possible that these plants aren't accumulating metal at all, and that they have adapted (or have been selected to become) very strong and flexible. Maybe they have adapted to the extreme environments of space by developing calcium exoskeletons; or maybe they've ceased to resemble lichen and moss as we know them, and they've evolved into some new category which is capable of (and maybe engineered for) producing materials like carbon filaments or crystalline silica deposits.

As I talked about earlier, 'chemicals created by plants' can include metals. They can also include various salts, minerals, organic deposits, and inorganic impurities, of course.

Without further details, it's hard for me to give more specific examples.

In what ways does the end result of micelis-crafting 'closely resemble' metal, and in what ways does it differ?

Related and distinct question: Is it possible that an impure alloy, or a very rough ore, could be mistaken for 'closely resembling' metal in this context? Or is this definitely a non-metallic substance we're talking about?

  1. http://www.huffingtonpost.com/2013/02/04/gold-bacteria-toxic-ions_n_2616566.html
  2. https://en.wikipedia.org/wiki/Iron_bacteria

EDIT: Here are some other relevant questions.

  • $\begingroup$ Micelis-based weapons are indeed more easily broken than regular ones, so, yes, what looks like metal could actually be a mix of ore and organic materials. I didn't know that plants could produce metals, and it definitely works in this world, thanks. As for the technology available : people on the spaceships regularly fix them or even upgrade them, so I guess their science would be at least as advanced as ours and probably more. $\endgroup$
    – Rebouh
    Apr 19, 2016 at 12:04
  • $\begingroup$ Cool! Edited my answer to include links to other relevant questions (with great info on metal-accumulating plants, etc). $\endgroup$ Apr 19, 2016 at 12:13

The antagonists from Magician (Raymond E. Feist) come from a world where there is little to no metals available, instead they've built shields and weapons from lacquered substances - including leather if memory serves - could you use this method in your setting?

Coat materials in a plant resin and cure them into shapes that can further be worked/sharpened.


There are two ideas I have about this.

First is purification. Maybe the hulls of the spaceships are made from metal alloy that is simply impossible to work with or separate using technology available to humans. But the micelis could separate the various components of the alloy, thus producing raw materials that then can be used for standard metallurgy.

Second idea is mold forming. The micelis simply eat whatever metals is nearby and grow into available space, filling it with eaten metal. So simply create a mold in form of sword and put micelis inside it and just wait. Depending on it's growth speed, it might fill the sword mold in a few months or years.

  • $\begingroup$ I like the idea of simply letting micelis fill a mould. But how do I make such moulds ? And which material will they be made of ? $\endgroup$
    – Rebouh
    Apr 20, 2016 at 12:03

So you have a colonial micelis that is grown in a mold of the weapon that you need, it naturally forms firm cellular links between the individual micelis so that they're effectively a single larger organism. They don't live long in this formation but they can be feed a metal salt solution that they convert into a solid-ish form that mirrors their shape. Basically you end up with a weapon made from metal structured to resemble coral, it's solid enough, slightly lighter than a forging would be and a bit rough in the raw but it would work just fine, in fact it would be slightly more shock resistant than solid steel.


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