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Festering Fungus
"Stay back! The plants kill!"
— Sign outside of Vault 22, Fallout: New Vegas

The Festering Fungus is a fictional lifeform usually based on a mold or a lichen, know for its rapid growth rate and destructive tendencies.

The effects of the fungus will vary. The Lighter and Softer versions will usually just cause structural damage to buildings, cars and trees, while the nastier versions start growing on people, resulting in all sorts of Body Horror. Ingesting the spores of this lifeform is to be avoided at all cost.

This type of lifeform tends to make for a good Monster of the Week. After all, it's usually nonsentient, so you can finish it off for good without feeling guilty about it. The protagonists will usually find a way to stop it by the end of the episode, often with the aid of some fantastical fungicide or by dropping the temperature so that it can't grow.

In a comedy series, expect it to have crawled out of someone's refrigerator. See also: Alien Kudzu, Fungus Humongous, The Virus. Mold-based variats may overlap with Blob Monster, Muck Monster, or Meat Moss. People infected with one of these may become Poisonous People. Often a Puppeteer Parasite.


Anime & Manga
  • In the episode "The Sound of Rust" of Mushishi, A fungus-like rust infects a girl's vocal cords, and whenever she speaks, rust spreads like lichen across her village, and even on the skin of the other villagers. The girl becomes a pariah to her people due to her connection with the plague.
  • Episode 229 of Naruto Shippuden titled, "Eat or Die! Mushrooms from Hell!" had multicolored mushrooms called "Moulding Mushrooms" overtake the ship on which the team is sailing. Upon being eaten, the mushrooms sprout from the eater's skin and influence their actions.
    • This is probably yet another "The Voice in the Night"/Matango Homage.

Comic Books
  • Spirou and Fantasio: The Count of Champignac is a mycologist who uses a very fast-growing mutated mold as a bio-weapon. In one instance, said mold destroyed a city-sized secret base in just a few minutes.
  • Morrigan Lugus from Supergod is a superhuman entity made up of 3 unlucky astronauts fused together with alien fungus to form a sentient mycological supercomputer. The facility it's kept in has to be cleaned over with bleach almost constantly to prevent mushrooms from growing everywhere, and before the science team started taking anti-fungal medications, several of them died and during the autopsy it was discovered that their lungs were filled with fungal growths that looked like deformed human faces.
  • In the first Hellboy miniseries, one of the Ogdru Hem (which mutates humans into frog monsters) is defeated and killed with fire, or so the heroes think. In the B.P.R.D. spinoff, this monster grows back and is revealed to be a fungus. It's ability to mutate humans turns out to be an effect of its spores.
  • Tom Strong had a story in which an obnoxious dotcom billionaire who decided to play-act as a pirate got killed by a group of real pirates who had become infected and preserved by a "Voice in the Night"-style mould.


  • The Ur Example may be the 1907 short story "The Voice in the Night" by William Hope Hodgson.
  • The 1923 story "Fungus Isle" by Philip M. Fisher.
  • The often-mentioned, never fully-explained "mold demons" from The Dresden Files that ate all the organic matter in Harry's car. Including the seat cushions. But hey, at least the floorboards are really clean now.
  • Expedition Venus by Hugh Walters has Earth threatened by a fast-growing mould brought back to Earth by an unmanned space probe. Includes some disturbing descriptions of what happens when it grows on people. (As the trope description says, it's a Monster of the Week — this is the fifth novel in a series — and the heroes sort it out by the end of the novel.)
  • The title city of Ambergris is prone to this, and positively swimming in it by the time of Finch. Related to rule by the Graycaps, who are themselves a spore-based lifeform.
    • The Graycaps themselves are not spore-based creatures; they are described having two genders and reproducing much like humans, and the urban legend that they hatch out of mushrooms is debunked by the most reliable authority in the books, Jonathan Shriek. They do, however, live in constant symbiosis with fungus and allow themselves to be infected with various kinds that have beneficial effects to their physiology. They can communicate telepathically by blowing spores over each other and their flesh is so riddled with fast-growing fungus that small wounds close almost instantly, making them difficult to kill.
  • Robert Westall's Urn Burial has harka, a fungal mould created by the Attock which primarily infects the females of species and kills young developing in the womb. In adults it just eats away their flesh and strips them down to the bone. The only way of killing it is to teleport the infected into stars.
  • Byrus from Stephen King's Dreamcatcher looks like a red mold and grows across any surface it's exposed to, whether inanimate or living. Internal exposure can result in the growth of a fatal parasite called a byrum (or more colloquially a "shit weasel"), but most never reach that level, and many of the infected have a good chance of survival.

Live-Action TV
  • The aforementioned William Hope Hodgson story "The Voice in the Night" was made into an episode of the TV show Suspicion in 1958.
  • These things were in the spotlight of The X-Files episode "El Mundo Gira". The guy who is infected is spreading the fast-growing deadly fungus to everything he touches.
  • Primeval features these in the third season. They take over the victim and turn them into a rather creepy monster that requires freezing or heating to kill. (Heating the fungus causes it to explosively scatter spores everywhere, which will start growing again if you Just Add Water.)
  • The last segment of The Future Is Wild, set in Earth 200 million years in the future, showcases the "Slithersucker", a slimemold that is capable of adopting the shape and color of a fruit so it will be eaten by a passing "Megasquid", a terrestrial squid the size of an elephant (squids fill the niche of mammals by that time). The Slithersucker escapes digestion and divides in two group of cells: one moves to the "noses" of the Megasquid, the other to its brain. The one in the brain takes control of the Megasquid's actions, moves it around to a suitable location and then makes it "sneeze" to facilitate the dispersion of the cells in the respiratory system of the Megasquid, while the cells in the brain are ultimately eliminated by the Megasquid's inmune system once dispersion has been completed. This is inspired by modern day fungi that infect snails and arthropods, as detailed in the Real Life section.


Video Games
  • The Pokémon Parasect is a tragic victim of one of these. Its pre-evolution, Paras, has a symbiotic relationship with the Cordyceps-like fungus growing on its head, but when it evolves, the fungus takes over its body completely, leaving it a blank-eyed zombie bug.
  • NetHack has a number of mold mobs, palette-swapped by how they hurt you.
  • Phazon, from Metroid Prime, is most often encountered in the form of a highly radioactive, rapidly growing, seemingly sentient fungus that either kills or corrupts anyone or anything that has contact with it for too long.
  • Fallout: New Vegas had these as the result of experimenting with genetically altered spores. They're found in Vault 22 and in the DLC, Zion Valley and Big M.T., where they were originally created. Worst of all is how you can find "Runts" in Vault 22 as well as baby carriages covered in spores.
  • The Last of Us has a mutant strain of Cordyceps that infects humans as the cause of the After the End setting.
  • The Minecraft mod Thaumcraft features Taint, which covers the ground in toxic slime, melts trees into goo and turns any mobs that die from the poison into Tainted versions of themselves that either spread the Tainted Land biome or just attack untainted mobs. Tainted Land also features its own unique monsters, like swarms of stinging bugs or large tentacles that grow from the ground.

Web Original
  • When the housemates of the eponymous Sex House realize they're unable to throw away their moldy food, they end up storing it in one of the unused bedrooms. The mold eventually takes over the room, and in episode 8, the repairman the cast takes hostage and chains up in there dies from it.

Western Animation

Real Life
  • Cordyceps are a type of fungi that infects living creatures (mostly insects and other arthropods). They grow inside the infected bug until it kills it, at which point the fungus bursts out of the host's exoskeleton and flowers, spreading its spores. Even creepier is that some species of cordyceps actually affect the host's behavior. For instance, one species infects ants. The infected ants gain a compulsion to climb upward as far as they can before they die, which allows the cordyceps to spread its spores further.
    • The really fun part is that it is commonly eaten by humans, and is even used in many medications such as the anti-rejection drug Neoral.

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