Item: SCP-1345-RU
Object class: Euclid

SCP-1345 mycelium part, sprouted from the wall
of the building to the closet

SCP-1345 sporocarp half an hour after
Foundation personnel has entered the building

SCP-1345-2 shortly before capture
Special Containment Procedures: Anomalies found in water supply systems in northwestern Poland are continuously monitored by the Foundation. Upon detection of SCP-1345 activity, a cleanup group is sent to the site, the building is treated with fungicide and demolished, and the debris are transported to the nearest Disposal Area. Civilians exposed to the object are provided with necessary medical care, after which they are treated with class B or C amnestics at the discretion of medical staff. In case of poor prognosis of infection, elimination is allowed- any remains are to be cremated.
SCP-1345 spores and other biological materials are contained in cryo-storage in a High Value Item Storage Facility.
Description: SCP-1345 is a parasitic fungus exhibiting the anomalous ability to grow through most standard building materials, replacing them with a functionally similar mycelium structure.
The definitive hosts of the parasite are residential buildings of any design with access to water supply systems (henceforth SCP-1345-1). Although the reproduction mechanism of the object usually leads to its appearance in functioning buildings, it can also develop in abandoned houses. Infection typically begins in the basement, attic, or other premises with accumulation of water pipes. At this stage, the fungus develops using previously accumulated resources (see below), making its way through the pipes to the water source. Once contact is made with the source, it begins rapid growth, replacing the materials of the building and its structures. This phase is characterized by the appearance of cracks in the walls of the building, numerous blockages and leaks caused by the growth of the fungus, and the spontaneous shattering of windows and other glass due to pressure differences. These factors combined leads the building to a state of emergency, with residents seeing subsequent evictions due to health concerns.
Growth of the mycelium through the building is completed within 3-5 months after the cessation of repair work and cleaning of the premises. At this stage, the fungus begins to restore damage to supporting structures, broken windows (openings are filled with a dense organic translucent mass resembling heavily soiled glass), broken doors (although the structure is restored as a whole rather accurately, the growth of SCP-1345 through hinges makes them almost non-functional), etc. Over time, the object merges with the remnants of all other objects in the building, replacing lost sections of wallpaper (the color is not copied, the replaced areas remain dirty - beige color with stains), carpets, and curtains, as well as partially restoring furniture (upholstery of sofas and chairs).
Despite the fact that the water absorbed by the object causes a significant increase in indoor humidity, buildings affected by SCP-1345 remain an attractive shelter for marginalized populations due to structural integrity and partially functioning water supply systems. Whenever people appear in an infected house for some unknown reason at this time (see Appendix 2), mass germination of the sporocarps begins in the ventilation shafts, the joints of the walls, the floor, and any water pipes. Appearance resembles Psilócybe semilanceáta. These sporocarps contain a unique set of psychoactive substances, where absorption through any means causes short-term euphoria and hallucinations.
The transition to an intermediate human host (hereinafter referred to as SCP-1345-2) begins slowly. Guaranteed infection occurs only if regular and continuous breathing of infected air occurs for around 3-5 days. Early symptoms may include irritability, insomnia, and a mild rash. Patients enter a depressed state, though short-term relief may be achieved by ingesting fruiting bodies of the fungus. Cases of paranoia and persecution mania are also noted, gradually increasing as SCP-1345 develops in the host's body. At this stage, standard drug therapy is enough to cure infection.
The object’s development within SCP-1345-2 takes from 3 to 9 weeks, depending on the circumstances. Completion of this process is characterized by occurrence of acute obsessive-compulsive disorder, which manifests in an irresistible urge to wear as much clothing as possible. Subjects claim that they feel "naked" and refuse to undress, regardless of the circumstances, under the excuse that they are "fine as they are". At the same time, other symptoms reach respective peaks, and the infected start to show an extreme degree of distrust towards everyone except other instances of 1345-2. Obsessive thoughts of pursuit force -2 instances to escape from SCP-1345-1, eventually causing formation of small groups, and adoption of a wandering lifestyle.
Physical symptoms at this stage manifest in formation of small ulcers on SCP-1345-2's skin, from which SCP-1345 mycelium spread outward. The fungus gradually grows through all surrounding materials, splicing the host's body with said materials and absorbing moisture from the environment (SCP-1345-2 at this stage like to spend time in the rain, puddles, fountains, and other reservoirs). The appetite is greatly increased, and weight gain contributes to the further interpenetration of the tissues of SCP-1345-2 and the items they wear. Healing in such situation requires a course of chemotherapy, surgery, and a long course of psychotherapy.
The final stage generally begins after SCP-1345-2 gains around 120-140 kg of excess weight. At this point, the fungus begins explosive growth- the mycelium sprouts through the entire volume of objects in contact with an infected person, pulling out various tissues and organs between the layers of clothes and functionally replacing the connections between them (vessels, ligaments, etc.). This process, like much of SCP-1345-2's vital activity at this stage, is extremely painful. At the same time, growths begin to appear on the surface of the outer layers, almost identical in appearance to the sporocarps of SCP-1345, but without reproductive functions. These growths exhibit richness of analgesic compounds that, when consumed, have effects similar to morphine.
SCP-1345-2 at this stage lead a sedentary lifestyle. Higher brain functions are rapidly fading away, which is only aggravated by the constant consuming of growths appearing on them; in most cases, instances devote entirely to the search for a possible permanent shelter. Usually, it is a basement or other technical room of some kind in a residential building. Once there, the infected try to find an area hidden from strangers, where they are press themselves against the walls and stop motor activity, thereby allowing SCP-1345 to begin a new cycle, growing through the house's structure and completely absorbing SCP-1345-2(see Appendix 2).
Discovery Log: On 02.06.2005, a group of homeless individuals were detained by the police in Gdansk, all of which turned out to be SCP-1345-2 at various stages of infection. Reports of the strange state of the detainees were quickly intercepted by the intelligence services of the Foundation. The timely intervention helped to avoid the dissemination of information about the anomaly, and the infected were taken to the nearest Biological Site. All witnesses were treated with amnestics.
Further investigation revealed seven SCP-1345-1 among abandoned buildings in various locations in northwestern Poland. Have been identified, all instances were found to be connected by similar readings of fungus activity in their respective water supply systems. Of all SCP-1345-1, the first one to be transformed (and, apparently, the source of infection for all the others) was country cottage of Mr. [REDACTED], at that time already missing for two and a half years. A thorough search made it possible to locate containers in the house with the remains of a large number of SCP-1345 fruit bodies, and among the documents - a letter indicating his connection with the Polish Anomalous Mushroom Picking Association.
Addendum 1:
Addendum 2: On 08/05/2017, during the inspection of another SCP-1345-1 instance, a patch of mycelium containing a whole human eye was found between the floorboards near the entrance to the building. [DATA EXPUNGED] The samples turned out to be fully compatible with the human nervous system. Tracing these structures, agents found [DATA EXPUNGED]. Possibility of retaining [REDACTED] is still in question.