I had a cool but not so original idea: aliens with many many redundant organs, and a nervous system spread across their bodies. This creates some issues. How do I kill one?

What the Alien is like:

The alien looks like a blob with lots of tentacles covering it. Each tentacle has a eye, mouth, fingers, and a digestive system. There is no heart, or lungs, or other vital organs. The aliens' organs are spread out through their bodies. Their bodies are about the size of a smart car and the tentacles are about 10 feet long. To move the aliens throw out their tentacles and drag themselves forward. By doing this they move about as fast as a jogging human. They are not particularly resilient, but they are wearing sleeves and a “vest” which will stop small caliber rounds and slower shrapnel. Naturally occurring latex will ground them if most of their tentacles are touching the ground. They came to Earth for all of the tasty snacks, which they prefer well done, so they brought lasers to cook humans with. These lasers will torch you if you are under fire for more than 5 seconds.

So I can’t kill it by shooting it through the body. Using only 21st century weapons how should my soldier kill them?

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – L.Dutch
    Jan 23, 2021 at 4:06

10 Answers 10


Let go of the Geneva convention


Gasses are incredibly dangerous. They can be invisible and odourless (for humans at least) but still have incredible effects. A nerve gas can destroy or temporarily lock down nerve fibres, killing or disabling the target. You can do corrosive things, or simply poison the enemy. As the aliens don't have lungs and I assume still need oxygen to live they probably take it up with their skins. This is a huge vulnerability, as the gas can be easily take up into the body and spread. In addition, you can potentially just suffocate the aliens.

They can potentially unfocus laser beams, so there's that as well.


Similar to gasses but focussing a bit more on the personally dispensed ones. A poison dart can be incredibly effective. Again, nerve agents can kill or disable the nerves. But poisons can do so much more. Besides directly killing cells, they can shut down organs or manipulate them to make toxins/degrade materials into (more) toxic materials. poisons can be shot, hid in food (cyanide capsule embedded in each soldier?) dispersed in gasses, liquids or just on the ground and be able to kill.

Biological warfare

Viruses and bacteria are present everywhere. They can go good stuff, or very, very bad. Multiplying in a body, taking resources, destroying cells, excreting toxins, making the immune system kill the host and more. There's also parasites that can eat organisms from the inside. Some can rapidly multiply and mutate itself, so whatever you throw at it is ineffective in the long run. In the end, you can't protect yourself against everything. A 21st century soldier might not even be present on the battlefield. You just fly over with a plane, dispersing a cloud the equivalent of a large cough and watch the aliens shut down from a distance.


It has been said in other answers, but fire is incredibly powerful. Movies and games make it out to be a short ranged weapon. Although it definitely is short ranged, human portable could still reach 40 meters (45 yards) and tank mounted ones 90m (100 yards). Napalm was done for large area's by planes as well. Although the Geneva convention prevented further development, I'm pretty sure we'll be able to make new more effective fire based weaponry. The reason we can fire that far is because we're throwing fuel, which is then ignited. The fuel often has damaging properties as well, like boiling while ignited. So being sprayed upon will keep damaging long after. As suggested, the sheer damage, the stress and/or the bacteria afterwards can all be enough to kill the organism after.

Brute force

We have machine guns that can spit out so many rounds a minute with such force they can splinter trees and set them on fire. We have machine guns mounted on planes that can output more force than the plane's engines can, potentially propelling it backwards. We have tanks with solid shells that can rip anything apart. Explosives that don't even need to hit you directly and can kill you due to the shock-wave. And finally we can just drop a concrete slab with a helicopter on top of an alien for style.


There are many, many ways to attack organisms with distributed organ systems. We haven't even talked about bleeding them dry, simply putting spikes in the ground or the tactic of scorched Earth. Pick a few and call it a day. Humans have a great scary arsenal to their disposal for both long range as well as short range battles. The humans will be fine.

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    $\begingroup$ +1 just for the lead-in "Let go of the Geneva convention" -- reminding people that in a struggle for the survival of humanity, all tactics must be on the table. $\endgroup$
    – arp
    Jan 21, 2021 at 1:20
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    $\begingroup$ ‘Let it go, let it go’ $\endgroup$ Jan 21, 2021 at 9:31
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    $\begingroup$ +1 for just checking the list of things that makes even the biggest warmongers in the world say "that's a bit much". $\endgroup$
    – Erik
    Jan 21, 2021 at 13:21
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    $\begingroup$ The term you are looking for in the Brute force paragraph is "hydrostatic shock". $\endgroup$
    – hyde
    Jan 22, 2021 at 7:34
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    $\begingroup$ @Fivesideddice : Yes, play that song to it enough times and the alien WILL commit suicide $\endgroup$ Jan 22, 2021 at 9:05


Fire is a great killer because (for any creature with a reasonable amount of body fat) it’s self sustaining. Once a fire reaches a certain temperature it starts using the flesh of the creature it’s burning as fuel, leading to massive trauma and rapidly spiking internal temperatures. Even if a creature survives it burns create a huge surface for bacteria to enter the body through and can lead to scarring/debilitating injuries/just death through shock.

Pour on gasoline, flick a match, watch all those lovely distributed organs burn.

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    $\begingroup$ Yep, flame throwers are old tech. $\endgroup$
    – Kilisi
    Jan 20, 2021 at 13:31

Acid or fire.

throw acid on it or burn it, if it has not specialized organs it is breathing through its skin which makes the skin very weak and vulnerable, burn it with acid or fire and it will suffocate.


this thing will be very vulnerable to poison with no specialized organs it can't filter its body fluid effectively so poison will be more effective.

Push it around.

without lungs this thing will be slower than molasses you can just use a construction equipment to pick it up and dump it in a fire pit or some other disposal area.


again with no breathing organs it is breathing through its skin, which means the skin needs to be moist, throw salt on it and it will either suffocate or dehydrate. there is a reason multicellular life evolved organs fairly quickly.


How Did Hercules Kill the Hydra?

The ancient Greeks had to deal with such a monster.

enter image description here

Defeating the Hydra was the second labor of Hercules, and it was a job that would require both strength and wits to accomplish. https://mythologysource.com/how-did-hercules-kill-the-hydra/

As Hercules cut off each of the monster’s heads, Iolaus followed behind with the torch. As soon as one of the heads was removed, he used the torch to cauterize the wound.


If we assume that when the said alien loses its tentacle it is similar to us humans losing and arm then it is easy to kill them but I do not think that is what you meant. Assuming after cuting off a tentacle alien, perhaps the tentacle itself too, would still continue to live, the solutions left that I can see are:

Burn them

Using a flamethrower your soldiers can cook them alive.

Use explosives

Explosives will surely kill some of the alien's tentacles if not all. It will at least hurt it real bad so that your soldiers can cook it alive as mentioned above.

Use acids

Dissolve the aliens with powerful acids.

To sum up, just destroy its body chemically. It is the easiest way.


Killing them softly with his song

Use sonic weapons. You may think these are early 21st century tech but this is actually early 20th century tech, so it should do.

The scene in the link is from Mars Attacks, a rare non-goth movie from Tim Burton.

The Oldsmobile

Take a page from the best trash movie trilogy ever (The Evil Dead). Protagonist Ash Williams modifies Sam Reimi's car (true story!) into a killing machine by jury-rigging a medieval helicopter's rotor and blades onto it, at an angle. He then mows down a horde of undead with it. Bonus if you also fortify your ride with armor, and make it run on steam for environmental friendliness.

This is actually Sam Reimi's car.

Nuke from orbit

I'd bet 10 canadian dollars that those aliens' body armor won't withstand a nuke at point blank.

The Soviet RDS-220 hydrogen bomb, known by Western nations as Tsar Bomba, was the most powerful nuclear weapon ever created (...), it also remains the most powerful explosive ever detonated.


The raw boldness of this move will scare them from ever attacking the Earth again.

Sheer cold

If the aliens come during the winter, move all the population of the world onto Siberia. No one can invade Russia during the winter.

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    $\begingroup$ I am disappointed in you for not having an image from The Thing or Terminator 2 for sheer cold. Downvoted. $\endgroup$
    – DKNguyen
    Jan 20, 2021 at 22:02
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    $\begingroup$ I don't have any details at hand, but Russia, to this day, maintains Soviet-era motorized mortars with nuclear capabilities. $\endgroup$ Jan 21, 2021 at 13:02
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    $\begingroup$ @DKNguyen Or for that matter, The Blob. (Not The Thing though - it lived in the Antarctic, it was evidently fine with cold.) $\endgroup$ Jan 21, 2021 at 15:25
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    $\begingroup$ @DarrelHoffman I thought it was frozen until thawed $\endgroup$
    – DKNguyen
    Jan 21, 2021 at 15:27
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    $\begingroup$ @DKNguyen I guess it depends which version you're talking about. The frozen-in-ice origin wasn't added until the 2011 prequel. In the original 1951 film, it was explicitly from another world. Heck, that was even in the title: The Thing from Another World (though that version took place in the Arctic, not the Antarctic. Still cold though.) $\endgroup$ Jan 22, 2021 at 15:25

A microwave cannon.

Easily buildable using off-the-shelf technology, has relatively precise aiming and area of effect (unlike flamethrowers, explosives, and acid), limited collateral damage, and the power requirements are manageable. The military has already built low power vehicle mounted versions for crowd control so the technology is known to them and various experimenters have built small crude ones using components from microwave ovens.

  • $\begingroup$ And the crowd control ones have been promptly stopped from deploying over the risk of blinding people (not that it matters here) $\endgroup$ Jan 21, 2021 at 13:03

Rocket propelled grenade launcher

Or similar weapons - eg: shoulder launched anti-tank weapons. Grenade if you're desperate.

A decent Kaboom solves many problems. The tentacles wont be able to work together if the nervous system is disconnected and scattered over a city block.

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    $\begingroup$ Honestly this is the answer. You don't need to do anything unusual, no need to even break the geneva convention. It's not Godzilla or The Thing, it's an octopus with a laser-cannon and clothes. Blow it apart with a grenade and go home. $\endgroup$
    – Ruadhan
    Jan 22, 2021 at 8:31
  • $\begingroup$ The OP may be mistaking "decentralized organs" with something like the T-1000, the Blob, or the Thing which is effectively amorphous and so decentralized it doesn't even have organs. $\endgroup$
    – DKNguyen
    Jan 22, 2021 at 20:18

Explosives have been raised already, I will raise a specific kind:

Thermobaric weapons

Being essentially a giant blob with tentacles, with little rigid structure, those aliens are presumably very susceptible to high pressure. Assuming the fuel is toxic to the aliens, you get even more fun, since sometimes it's not burnt completely.

The [blast] kill mechanism against living targets is unique—and unpleasant. ... What kills is the pressure wave, and more importantly, the subsequent rarefaction [vacuum], which ruptures the lungs. ... If the fuel deflagrates but does not detonate, victims will be severely burned and will probably also inhale the burning fuel. Since the most common FAE fuels, ethylene oxide and propylene oxide, are highly toxic, undetonated FAE should prove as lethal to personnel caught within the cloud as with most chemical agents.

So, you then get:

  1. squash
  2. burn
  3. (sometimes) poison

all in one weapon.


Flame thrower is a very deterring weapon, but actually not very effective. It could work, but it would not be very effective. It makes far more enemy to flee, than actually kills.

I think with such a fast metabolism, they are lesser prone to poison: if they regenerate quickly, they can also process the poison quickly.

However, quick cell multiplication also means that their cells reproduce also viruses very quickly. It is because virus doesn't reproduce on its own, it reproduces by manipulating the infected cells to produce it.

If a fatal virus infection would take weeks to kill a human, it would be a visible change in the alien and would kill it in minutes, maybe in hours.

Note, such a fast metabolism requires many energy, i.e. food. The aliens would need to eat a lot, quickly, particularly if they have wounds.

If the virus kills the alien quickly, it also means that they can not infect enough other aliens.

In the case of human biological warfare, it is exactly the goal, i.e. to kill faster, or to use not very well transferable bacteria. It is to prevent the back-firing of the weapon. This problem would not exist in the case of the alien, because the virus affecting them would not affect the humans.

Thus, the virus particles ("cells") must be used as a chemical warfare, in aerosol form.

Alternatively, we could also use suicide attackers, infecting themselves with the virus. Alien kills them, eats them, and they get the virus with them. This could also "motivate" them to think a little bit before dinner.

Developing a virus against an entirely unknown alien life-form would take a lot of time. Because they can eat us, they need to have a similar protein structure than the life of the Earth. This makes likely that they can be affected by our viruses, or by similar ones.

A living alien, or more living aliens need to be captured, and then infected by all the - mostly, not lethal - viruses we have in all our class 4 labs. Then find the ones most capable to exist in them.

Then, modify these - ideally by crossing them with a similar, but deadly virus.

  • $\begingroup$ You're aware that flame-throwers in real life are nothing like the ones you see in video games? Real flame-throwers are one of the most obscenely lethal anti-personnel weapons ever devised. while yes, it definitely makes the enemy run away when they encounter one, that's because they'll get turned to a pillar of screaming bacon if they stay. Picture a water-cannon blasting a jet of burning napalm long enough to cross a foot-ball field and flood a bunker with firey death. Real flame-throwers are nothing like Elon Musk's roofing-flamer. $\endgroup$
    – Ruadhan
    Jan 22, 2021 at 8:36
  • $\begingroup$ @Ruadhan There are various pictures and videos around the net about real flame throwers used (or usable) in real battlefield. As far I know, a squad with flame throwers has no chance on the battlefield against a squad by ordinary submachine guns (in most cases), except if they can use the terrible deterrent effect. Typically flame throwers are used in squads that there is 1 soldier with flame thrower, and the others fight with guns. $\endgroup$
    – Gray Sheep
    Jan 22, 2021 at 9:15
  • $\begingroup$ Flamethrowers are comparatively short-ranged and not as responsive vs a gun. But they definitely 100% are excellent at their actual job, which is killing enemies who are hiding in or behind cover. In WW2, their main use was in pouring burning napalm into fortified bunkers via the gun-ports and doors. In Vietnam they were popular for their ability to turn the excellent cover of a jungle into an inferno. Against the blob-monster from mars, you just have to get close enough to douse the target in napalm.. So anywhere within 100m should do fine. $\endgroup$
    – Ruadhan
    Jan 22, 2021 at 9:29
  • $\begingroup$ Flamethrowers are in no way merely a deterrent, if they get fire on target, that target will die horribly. But they're close-ranged and take a moment for the jet of burning fuel to reach its target. Great for clearing bunkers, less so for two armies charging across a field. But that hasn't been how we fight wars for most of a century now. $\endgroup$
    – Ruadhan
    Jan 22, 2021 at 9:38

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