The world is at danger because the death of one singular entity called heart of the world is dying. Artwork by PeteMohrBacher

Copyright 2014-2020 PeteMohrbacher

The question is how do I link the death of the heart of world to the mass extinct of most of complex life on the planet.

requirements are that the creature must be able to move, their size is gigantic and represented in the image above, the world is a spherical planet with a map consisting of mostly oceans, has way less land than our earth. Other creatures in this world mostly resemble earth like ecology in the sense that there are producers which get energy from the sun, or chemicals in deep waters creatures which eat the producers and we call them herbivores and creatures which eat the other creatures which eat the producers and we call them carnivores.

Gravity is slightly smaller than on earth but not enough to float with a jump like on the moon, the planet has a night and day cycle of 3 hours of night and 3 hours of day. The planet spins faster than earth as it lacks a moon which drags and slows it down. Breathable oxygen is found in the atmosphere and oceans of this planet.

The only thing that came to my mind was ammonia, since decomposers, like bacteria for example release ammonia when processing dead animals. But while certainly the creature in question might be enough to cover a small forest in ammonia, it is not enough to cause any mass extinction. Forgot to point out that ammonia is an irritating gass which can easily kill if inhaled or drank when mixed with water.

Ah yeah, obviously the question lacks the magic tag so answers which justify this as being magical are off topic.

I think that should be enough?

  • 4
    $\begingroup$ This question provides very minimal information, and could invite literally any kind of answer. It could profit from some more detail which would narrow down the direction you want to go in. As for now you're just asking for an extinction event which you could potentially link to this creature, which has literally no indication of whether an answer would be good or not. $\endgroup$
    – Plutian
    Jul 2, 2020 at 13:38
  • $\begingroup$ @Plutian how many ways are there to link the death of a singular entity to the Apocalypse? The question can't have more details because it's basically A dies and B dies too, so does the rest of the alphabet. The question is about the mechanism which makes it happen. Usually when a creature dies they leave space for more life to flourish not the contrary. $\endgroup$
    – user76826
    Jul 2, 2020 at 13:48
  • $\begingroup$ when a roach is killed other than by stepping, it turns turtle... so ;D $\endgroup$
    – user6760
    Jul 2, 2020 at 13:51
  • $\begingroup$ @Don'tgotyousleeping There is no limit to creativity. I could answer saying the creature gets so enraged about dying it rampages and magics away every creatures right foot and they all die of infection. Or the creature expels a powerful magnetic field attracting asteroids to crash into the earth exterminating all life. Yet I have the feeling this is not the kind of answer you're looking for. Giving details to guide us to what kind of answer you are expecting will help us to give better answers, and prevents you trawling through heaps of answers which are completely useless to your story. $\endgroup$
    – Plutian
    Jul 2, 2020 at 14:11
  • $\begingroup$ @Plutian notice the tags...lacks the #magic... But if you could explain how a creature can output enough electronic power to destroy a planet by #biologycal means when it dies.... then please do so! If I knew what more details to add then I would've already knew the answer by myself. $\endgroup$
    – user76826
    Jul 2, 2020 at 15:23

5 Answers 5


To have one creature create such a cataclysmic event that it spreads worldwide isn't easy, especially if you want this done by purely biological and even plausible means, but it isn't impossible.

The approach I would suggest is the creature is a remnant of a feeble worldwide symbiosis, the last pillar of a reversed pyramid, unwittingly keeping the world from total collapse by its sole existence. You will need to create a completely new ecosystem with this creature at its very core.

It is said that if all the bees on earth die, the human race will follow within 4 years. Now killing all the bees on earth is not an easy feat (although humans seem to do a pretty decent job none the less), but it would be much easier if the existence of all the bees depended on this one creature.

The origin of the heart of the world species (from now on abbreviated as HOTW for ease) lies millions of years ago, and it was one of the first advanced creatures to evolve on this world. Due to the lack of natural predators at the time, the HOTW were soon in abundance throughout the earth. As an unnecessary (yet at the time harmless) side effect of its evolution, it started producing a rare gas as waste material. Since the HOTW were abundant, the gas soon was as well, and other creatures evolved which relied on this gas for their existence. In reaction to this, more creatures evolve which feed on these other creatures, and so on and so forth. This is your basic food pyramid, one creature produces something another feeds on, and over several hundred millennia a balance is formed, with the HOTW species as one of its pillars.

But then a predator arises, the World Killer (WK) species, which upsets this balance. It is not content with its place in the food chain, and evolves an intelligence and strength which allows it to feed on the HOTW species, a species which before went unchallenged. Due to the abundance of their prey, soon the WK are in abundance as well, wreaking havoc on the HOTW population throughout the world. With no previous need for self defence mechanisms, this is an extinction event for the HOTW species, like we have seen countless of on our own earth.

Now the issue is how quickly this happens, almost like a virus killing its host, the WK species spreads throughout the world slowly but surely eradicating one of the very pillars of the ecosystem. Suddenly the gas the HOTW produce is not as abundant anymore, and the ecosystem slowly but surely starts to collapse. With most of their prey gone, the WK species either evolve to prey on something else, or dies out due to lack of food. Either way, the damage is done. The HOTW species is all but gone, and the current ecosystem is dying with no hope of recovery. For life to continue on this planet, it will need to evolve a completely new ecosystem with a different base.

The only thing slowing the collapse of the current ecosystem is a few remnant members of the HOTW species, who as by a miracle managed to escape extinction. Yet soon they also reach the end of their lifespan, and with their potential mates scattered throughout the earth with no way to reach them, they die alone without offspring. Soon enough, only one very old, but gigantic and potent HOTW exists, the sole source of the now precious gas slowing the death of the current ecosystem. Once it dies, soon their symbiotic species will follow, and whatever else relies on them.

The truth is, the world as you know it will die either way, and saving this creature will only delay the inevitable.

To create this creature, you will need two things. First of all a basic breathing system which produces a waste gas. As most creatures on our earth consume oxygen, this isn't unthinkable, and as this is a fictional world, you could use any gas that reacts with a lot of material your life could be based on. Creatures in our world are carbon based and react with oxygen, but yours don't necessarily have to. Also, it doesn't even need to be a gas, but as Halfthawed pointed out in their answer, this is the easiest way to spread a necessary resource throughout the earth. Any other rare resource would do, as long as you have a system to distribute it.

The second is an extraordinarily long lifespan compared to the other creatures in your world. You could create a turtle-like creature which has the same characteristics as an immortal jellyfish. I've seen a few questions come by on this site which would help you towards the validity of such a creature. The point of this lifespan is that from the objective of other species, this creature seems to live forever. It has been there when they were born, and will be there for a long time after. Bringing an especially intelligent species to think it is indeed immortal, and that if they save it, they will save the world. Which in reality, is unsavable.


You know why people are so scared of nuclear weapons? Because if enough are detonated, the world would become a radioactive wasteland plagued by nuclear winter. That's the reason why nukes are more for being shown than for being used, because everyone is at risk of getting caught in the blast in a way or another.

Same thing for the heart of the world, whose internal structures and core are massive and composed mostly of radioactive uranium and plutonium. The creature, for some reason, has vast amounts of radioactive materials in its insides, resulting in something with enough fissile material within itself to make the tsar Bomba look like a banana of dynamite, should it explode. Luckily, as long as the creature remains alive, the inner mechanisms which would trigger these radioactive compounds from reacting and exploding will remain inactive. The planet's heart is basically a colossal, living WMD whose survival must be ensured to prevent the destruction of earth.

  • 2
    $\begingroup$ So the so-called "Heart of the World" is really more like "Planetary suicide bomber demon"? It's not so much that it is required for life as much as it is that it can't die anywhere on this planet without taking everything else with it. $\endgroup$
    – DKNguyen
    Jul 3, 2020 at 2:25

It's possible. But the extinction level event you have in mind will take centuries and possibly not even happen. Let's start at the beginning.

If we wipe out all of plant life on Earth, the Kingdom Animalia will slowly follow. Plants turned exhaled carbon dioxide into oxygen, which animals then use to breath and exhale into carbon dioxide. This is a wonderful example of symbiosis in nature.

Let's say this 'Heart of the World' creature has a similar symbiosis with the rest of the world. However, we're kind of restricted here - it can't be carbon-dioxide-into-oxygen, because it's one creature and the world is really big. There's no way it can produce enough oxygen. Instead, we're going to figure out what kind of symbiosis it has.

  • It's a rare co-factor: Because the Heart of the World needs to supply the world with this chemical, it needs to be something essential, yet is only required in a short supply. This means that this chemical is a catalyst, or, more likely, a cofactor. In fact, given the sheer implausibility of this scenario, naturally evolving, at a guess, this planet was artificially engineered to be as such. The Heart of the World produces this rare cofactor and then zygotes are specifically genetically modified to required the cofactor before being development - or something similar.

  • The chemical it produces is a gas: The chemical needs to spread to the four corners of the planet in question, and unless the creature ranges everywhere, (which means that it can survive every climate) the only viable method of delivery is diffusion through the atmosphere. This is take centuries, or even millenia to accomplish, but it is possible, especially if the creature is able to travel to most places in the world. Still, a gas is preferable. The gas is also heavy for a gas. This is just because we want it concentrated in the lower atmosphere - it doesn't need to be that heavy.

  • There's a secondary delivery system: Unfortunately, cofactors aren't gases. So the first two conditions contradict themselves. Fortunately, there's a way around it - plants. All plants on this planet contain within themselves a process that creates the cofactor, but only in the presence of whatever chemical that the Heart of the World produces.

So, to recap - the Heart of the World produces an airborne messenger gas (it's basically a hormone) which then goes to plants and triggers the plants to start a process to create a cofactor which is required for the procreation of life on said planet. If the Heart of the World dies, this gas stops being produced and, eventually, after the course of hundreds or thousands of years, will cease existing in the atmosphere, thus leading to mass extinction. Assuming, of course, no plants mutate in the interim to produce the cofactor anyway.

  • $\begingroup$ "Slowly"? I seem to recall another question here about what would happen if all plant life suddenly died. IIRC, a year before total collapse of all life was optimistic. $\endgroup$
    – Matthew
    Jul 2, 2020 at 18:58
  • $\begingroup$ @Matthew The air is so saturated with the gas hormone that it will take a while for the plants to stop. That's why it will take a while. $\endgroup$
    – Halfthawed
    Jul 2, 2020 at 19:05
  • $\begingroup$ Ah, I see, the plants are only wiped out slowly. Strictly speaking, that's not how the sentence reads... "If we [slowly] wipe out all of plant life on Earth, the Kingdom Animalia will follow" would have confused me less... $\endgroup$
    – Matthew
    Jul 2, 2020 at 20:42

Poison Pill :

This isn't the first time the ecosystem of the planet has been on the brink of collapse. The prior lifeforms had a metabolism deeply dependent on a specific element such as selenium as a cofactor. When most of the life was wiped out, your last survivor ate/absorbed all other organisms like it, and thus completely removed selenium from the environment. All selenium is in its body, and held tightly.

The ecosystem that evolved after has a DNA replication system that is vulnerable -REALLY vulnerable - to selenium poisoning, and DNA replication is an extremely conserved trait - it's hard to mutate this and survive. If this thing dies, especially if it dies in the ocean, as would be likely, concentrations of selenium would rapidly rise to lethal levels and sea life would collapse. It doesn't need to poison everything, just enough to cause a global environmental catastrophe.

An even nastier alternative is that there are millions of heart of the world spores around the world, shed by our good friend over the course of centuries/millennia. The young form of these critters is highly aggressive and will consume everything on the planet. Only problem is, they can't germinate without selenium. If our big friend dies, his babies wake up and eat the world. One survivor will remain after everything is eaten, and it will slowly absorb all the selenium out of the seas as it grows to adulthood...


There are two major sources of oxygen in the world: phytoplankton, and trees. In real life, a single aspen tree can grow into grove of enormous size.

Suppose this tree were slightly bit more successful, and colonised the majority of Europe, Asia, and Africa. This tree would be responsible for a large proportion of oxygen proportion in this world, taking over the formerly biodiverse forests. This singular tree might have extremely mild genetic variations over its entire 85 million square kilometre (33 square mile) span, and shares circulation over the same area.

After an extended drought in South America, followed by a few unfortunate thunderstorms, the Amazon Rainforest began to burn.

To make matters worse, this aspen grove, the Heart of the World (though more accurately, the Eastern Lung of the World) got a prion infection, leading to a spreading area of dead tissue.

With the Amazon Rainforest (the Western Lung of the World) aflame, and the Eastern Lung of the World dying from infection, the concentration of carbon dioxide in the atmosphere would increase, and the concentration of oxygen in the atmosphere would decrease. The Eastern Lung of the World can singlehandedly handle the oxygen requirements for the entire world when healthy, of course.

If the atmospheric concentration of carbon dioxide increases sufficiently, then two consequences are likely. First, the acidity of seawater will increased due to carbon dioxide dissolving into water and forming carbonic acid. Second, the mean temperature of the world will increase, leading to melting of polar ice caps.

Should this second effect be sufficiently severe, then trapped gasses in the ice caps will be released, possibly leading to a positive feedback loop. Further, sea levels will rise, destroying habitats near to the coast. This may cause the death of mangroves (which fill a different niche from aspens, so will likely have remained extent until this point), and the extinction of mangrove-adapted life.

The increase in seawater acidity will lead to mass die-offs of coral, removing the niches of many forms of aquatic life.

The reduction in concentration of atmospheric oxygen, and the increase in atmospheric carbon dioxide may lead to asphyxiation of larger land-dwelling life, larger insects, and some aquatic mammals. Since this also corresponds to lower concentration of oxygen in water, this may also suffocate much aquatic life.

Though not all life will perish (plankton, some plants, many arthropods, and most microorganisms will likely survive), this will constitute a mass extinction event.

The Heart/Eastern Lung of the World must move, so aspen trees don't exactly fit. However, we might loosen the definition slightly. The Heart of the World forms a symbiotic relationship with a species of animal, known as Dryads. These dryads are completely dependant on the Heart, which excretes a nutritious syrup from specialised trunks, from which the dryads feed.

The dryads, in order to protect themselves from predators, have evolved to look very similar to the tree trunks. Further, they are very protective of these trunks (damage near to a feeding trunk worsens the taste of the syrup, so the dryads do their best to protect all the trees).

The dryads also are influenced by the hormone content of the syrup; the composition of the syrup is in turn controlled by the complex interconnected root network (which behaves almost analogously to a brain).

Taken together, an outside observer would see "trees" come to life to protect the grove as a whole.

It is, of course, obvious that if the tree dies, the dryads will go extinct.

TL;DR: If a giant tree provides most of the oxygen in the world, then if it dies, runaway global warming causes a mass extinction event. The tree is actually two species: the producer which is actually much like a tree, and the symbiotic dryads, which protect and carry out the will of the Heart of the World. The dryads move, and appear to be the exact same thing as the Heart of the World.


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