I am writing a contemporary fantasy novel with sci-fi elements.
The antagonist is a member of The Mahos. Their race predates our universe.
They have an extremely high body temperature their skin is made up of volcanic rock and crystals (basalt, rhyolite, andesite, and obsidian). Their skin is hard and brittle. Their internal body temperature is over 1200c. They have magical abilities. I.e telekinesis, control fire.

The idea is that when they come to earth, although we are advanced our weapons are useless -- bullets simply melt inside them without causing injury. Similarly, grenades and bombs, because of their ability to control fire, aren't effective either.

Is it plausible for a species like the Mahos to exist?

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    $\begingroup$ How can they predate the universe, but consist of rock-types native to Earth and which formed way after the big bang? $\endgroup$
    – Erik
    Commented Aug 21, 2019 at 14:18
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    $\begingroup$ We cannot judge how plausible your race is unless we understand the limitations that you are trying to judge them against. if you are looking real world its a no. If its a high magic universe it is a maybe depending on how you want it to be. $\endgroup$
    – IT Alex
    Commented Aug 21, 2019 at 14:19
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    $\begingroup$ magic and reality checks should be kinda mutually exclusive... If they are magic, why would they not be plausible? $\endgroup$ Commented Aug 21, 2019 at 14:41
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    $\begingroup$ Currently it's not really possible to answer your questions. There is no constraints mentioned, so anything is possible if you as the writer want it to be. $\endgroup$ Commented Aug 21, 2019 at 14:50
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    $\begingroup$ @Renan Magic doesn't mean anything goes; nearly every magic system has some set of rules. The OP here needs to define those rules for the question to be meaningful. $\endgroup$
    – stix
    Commented Aug 21, 2019 at 14:51

2 Answers 2


Plausibility of your magic

Depends on the laws of your magic

Plausibility or Fun Facts about that body

We know:

  1. They have some sort of brittle and hard skin
  2. Their inner core is 1200 degree Celsius

Your claim is that makes them impossible to kill conventionally

My first concern is the inner temperature. 1200 degree is the property to melt stone http://hyperphysics.phy-astr.gsu.edu/hbase/Geophys/meltrock.html

  • So I also have seen different figures at higher degrees. So it seems possible that a stone skin not molten could exist. But it raises the question why your stone skin is hard and brittle while being heated from the inside. It seems possible that your skin has actually a more viscous state that is neither brittle or hard but simply hot and deformable but not molten.
  • another question is how such temperature is maintained. Are your aliens glowing or radiating heat? In that you will have a loss of energy that needs to be maintained. But how so? Do they eat a lot or do they draw energy from their surrounding? Bottom line is their energy consumption is high and that might be their weak point.

On the claim on not being destructible by conventional means. I think it is possible with the right means.

  1. Using a hardened projectile. It is known that those can go concrete and other material. Even more so already softened stone I’d imagine.
  2. Using chemicals that react exotherm with quick phase transition into gaseous state inside the projectile after penetration.

If you can do this..you can pop them from the inside eventually


I think the question boils down to "how much magic do I need to MAKE them plausible".

These are living things, so they need a metabolism to sustain their bodies. So these questions arise:

  • what do they eat to build up their bodies and regenerate wounds?

  • what do they eat, breathe or otherwise use for the energy to maintain their heat, fuel their thinking capacities and energize whatever their muscles are made off.

  • how do they actually move at all?

  • how do they procreate?

The first seems simple. They eat whatever rocks they require. The inside is hot enough to melt and the outside isnt heated so it cools off and solidifies, creating the outer "skin". Damage would naturally be healed by the holes that leak molten rock and hardens.

The second one is harder. With the temperature difference inside and outside of the molten rock monster they will bleed off a lot of heat away and would quickly solidify and die (assuming that too much deviance from 1200c will kill them). Maybe radioactive materials inside the rock can be excited for energy through the magic, but the careful balance of chemical reactions inside cells seems off-limits in a molten rock formation where there is little to control where and how the chemical reactions happen.

And their muscles? Pressure differences inside chrystalized formations of the rock? Pure magic?

Then the third option. How does it move? Its insides are molten so its outside needs to have the joints but extremely perfect joints to prevent leaking and any damage would mean both leakage and eventually the joint to lock up. Maybe some kind of chriystalline structure could worok but it wouldnt be very durable against damage. Again the creature would need copious amounts of magic just to function. And I havent even touched upon sediment forming and stuff floating to the top/sinking to the bottom.

And the last point, how would they ever get children? They cant carry them inside so they would have to build a mold and fill it with their own stuff and then... blow life into it?

It seems that for almost every stage of its life these creatures will require magic in some capacity. To move its arms and legs (indirectly through pressure or directly through manipulating their arms), they require magic to live, magic to move, magic to keep their temperature, magic to procreate... so they arent very plausible. That said, they are magic molten rock forms that somehow need something from humans enough that they try to hunt down and kill them, why would you need a plausible explanation for them to work at all?

  • $\begingroup$ Thanks for the replies they help a lot! I’ll take all on board and think through it more I understand it’s hard without knowing the full magic system etc. But I’m not going to write pages and pages. The answers will help me go into more detail and make it more feasible, I’ll do some more research! $\endgroup$
    – Bighead123
    Commented Aug 21, 2019 at 18:20

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