Feasibility of nurgle inspired species

Question

Nurgle comes from the Warhammer 40K universe, he is described as being the lord of plague or the god of diseases, decay, and destruction. I will, however, take away his god like attributes, and true to make nurgle into an advanced alien race.

Appearance and behaviors

The nurglonians are said to look like fungus covered humanoids, who Simultaneously have the appearance of rotting flesh. The rotting flesh and body covered fungus like appearance comes from the fact that these aliens are categorized as plantoids. The appearances do vary, with some looking like they have pustules, and hives filled with insect like creatures, which is suggested to be some form of symbiosis. The height of said species ranges from 6-7 feet to even 8-9 feet, and have heads that look vaguely similar to the plague doctor masks, this has arisen a theory that the common plague doctor mask was inspired by these species, but there is little to no evidence to back this up.

As a species, they tend to keep to themselves, but do show a passive outlook towards other species. They believe that rot, decay, and pestilence lead to growth and the formation of new life.

intelligence

These species are fairly intelligent, enough to the point of making worlds and creating new life. They will go from galaxy to galaxy, taking and making new diseases to spread across any habitable worlds. Generally looked down upon because of this act, they will occasionally make entire worlds and develop an ecosystem that revolves around rot and pestilence, where trees are covered in lichen, bugs infected with many blights and diseases, seas and lakes flowing with infection, mold infected grounds, and many many more.

When given the opportunity, these creatures will generally try to adapt any lower form of intelligence into their species, and try to make them adapt to their own beliefs without trying to cause any anger or hatred. Many worlds that previously had life, had gone extinct due to such drastic additions of diseases.

Other than their creepy and overwhelming beliefs, they generally try to aim for peace.

extra facts

It is speculated that these aliens might have all transferred their consciousness into a new body, discarding the old ones, this theory arisen from the fact that their DNA is comprised of various other creatures DNA. The aliens have a considered a single planet sacred, scientist believe that the reason for these aliens caring over a single planet above all others is because this planet is covered in a living parasite that is capable of processing and creating new diseases.

Could such creatures feasibly exist, if not, then why?

Answer 1

Parasitism ≠ Symbiosis

TL;DR Living creatures that support whole ecosystems of parasites and decomposers would evolve better mechanisms to protect themselves unless those ecosystems provided benefits.

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Appearance and Behaviors

• Humanoids 6-9 feet tall
• Plague doctor mask heads
• Plantoids

First off, we can justify such extreme humanoid heights by having your nurgles evolve on a world with lower gravity than Earth. Their plague doctor masks, although unusual, can be explained as exoskeletal features to protect their brains from parasites. I'm reminded of armored fish for some reason. Also, Worldbuilding has speculated about sentient plantoids in the past, so you'll find resources that could justify such a creature evolving posted on other questions. These first three attributes are at least justifiable, if implausible.

• Fungus-covered, rotting flesh appearance, pustles, hives + insects
• Believe rot and decay lead to growth and new life

Now we run into the biggest problem with these creatures by far. If your nurgles are truly rotting on the outside, it means their living tissues are being broken down by parasites and decomposers. There is no symbiotic, mutualistic way for one creature to kill another, and it isn't sustainable in the lifespan of either one individual or one species. Any creature subject to such extreme parasitism would either go extinct or evolve defenses.

Even if each parasite in the nurgle ecosystem provided a specific, measurable benefit, the sheer abundance of creatures feeding on one individual's body would be unsustainable. In essence, your nurgle would be eating to feed itself, to feed a whole host of fungi, microbes, and insects, and to heal itself all at the same time. It would also need to have an immune system weak enough to allow for so many parasites yet strong enough to stop it from dying from the next common cold or new virus.

The only reasonable explanation I have for this is that nurgles build layers of muscle tissue from the inside-out, like concentric rings of a tree. Extra body mass would add up quickly, and especially weigh them down because they are so tall. In this scenario, they would benefit from creatures that removed their dead skin rapidly. This is analogous to mites living on humans; the host provides shelter and food, while the guests do cleanup. Such a configuration would require specially adapted fungi/insects in order to avoid eating through the skin/muscle too quickly.

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Intelligence

• Intergalactic colonization

This is a tough one. Intergalactic colonization isn't feasible with our current understanding of physics, because galaxies are moving apart quickly as space expands. Advanced nurgles could colonize a whole galaxy, but they would not be able to travel between any non-neighbor galaxies unless you invent faster-than-light travel.

• Creating & spreading new diseases that drives many worlds extinct
• Create plague worlds

Diseases probably can't affect creatures from other worlds. This means your nurgles will have to genetically engineer existing microbes or synthesize new ones with the appropriate biochemistries - which is theoretically possible, but definitely the mark of a very, very advanced civilization. In this way, making "plague worlds" is plausible.

However, driving whole worlds extinct? Not happening. If nurgles believe decay promotes new life, and they're advanced enough to engineer alien diseases, they will calculate the exact amount of death needed to cause rebirth. Think Thanos snapping to kill 50% of all life instead of 100%. Their theory is sound, too: biodiversity increases when ecological niches are "freed" after extinction events, and alien diseases fit the bill.

• Adapting lower life forms into their species

This one isn't happening. Alien life forms have the potential to be built on completely different chemistries. Without total chemical, environmental and genetic redesigns, "species adapting" isn't possible, and it wouldn't be sustainable if it was.

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Extra Facts

• Consciousness transfer evidenced by patchwork DNA
• Living parasite planet making new diseases

I'm not sure what you mean exactly with the patchwork DNA suggestion. One plausible explanation is that the nurgle genome has many snippets that were clearly spliced from other known species, indicating that nurgles are a genetically engineered race. This doesn't necessarily imply consciousness transfer - just complex tech.

As for that living parasite planet - that's a whole other question. :)

Answer 2

They look like parasites, but are actually symbiotic

Most living things are infested with a diverse, complex microbiome consisting of countless species of symbiotic organisms - some of them helpful, like those that assist in digestion or produce important nutrients, but many of them simply harmless. The nurgles are a species that have not only embraced their microbiome, but actively cultivate it, striving to obtain as diverse an ecosystem as possible. Unlike most Earth-based creatures, whose main source of biodiversity is in the gut, nurgles actively promote the growth of ectosymbiotes by having pockmarked, oily skin that acts as an effective breeding ground for all kinds of microbes. The microbes do not eat their flesh or vital organs, but feed harmlessly on these nutritious oils.

Ironically, this behavior may have evolved to fight parasites. They come from a planet with a particularly ruthless form of parasite, which mutates so fast that it will overwhelm any immune system that is not capable of evolving just as quickly. Because of this, it became more practical for them to seek out harmless microbes that eat dangerous microbes, and "infect" themselves to protect themselves - similar to how we use fungus-based penicillin, and potentially phage therapy, to fight bacteria.

The more "filled out" an ecosystem is, the harder it is for new species to move in. By making their bodies habitable to harmless microbes and actively seeking out said microbes to "infect" themselves with, the nurgles make it harder for dangerous ones to move in, promoting long-term health.

This behavior could have led to a kind of sexual selection, where a nurgle with a highly diverse and interesting microbiome would be considered attractive to others of their species. Different colored and textured fungal growths, a complex aroma produced by millions of species of bacteria, and swarms of insects would be particularly appealing to a nurgle's eyes. This would doubtless reflect on their idea of "beauty" as a whole, and as they became civilized, they would seek to create ecosystems that filled as many niches as possible with as many species as possible. And since every large species could host countless smaller ones, they would of course create millions of those.

But despite what it might look like to a human, species infested by nurgle-bred microbes are in fact perfectly healthy - a nurgle seeks to create balanced and stable ecosystems, while parasites that kill their hosts ultimately die themselves and would therefore be undesirable from a nurgle's perspective. Even though they are covered with oozing pustules and putrid mold, creatures modified by nurgle "engineering" rarely seem to get actually sick, and go on to lead long, happy lives.