Special Containment Procedures
When an instance of SCP-511 is identified, the affected residence shall be quarantined and will receive the next sequential site designation.
Excepting one main entrance, sites hosting SCP-511 will have all points of possible entry or exit permanently sealed with appropriate building materials. The main entrance will remain locked at all times. Entry is permitted to Foundation personnel with written authorization from Level 3 or higher. All SCP-511 sites will be equipped with remote monitoring equipment allowing for 24 hour surveillance and a continual tracking of the numbers of SCP-511-1 inhabiting the site.
At all times one (1) Class D personnel will be resident in the site. Personnel with this assignment are exempted from monthly termination for the duration of assignment. Candidates for this assignment shall be exclusively drawn from a population of post-menopausal women with a global Clinical Dementia Rating of 2 or greater. (Note: due to the exclusive nature of this population, O5-█ has approved recruiting from local hospice and/or nursing homes if necessary. Ref: Incident I-511-11)
The population of SCP-511-1 within a site must remain within an optimal range of 50 to ███ individuals. Below this range, adult Felis domesticus should be introduced to the site to increase population to minimum levels. If population exceeds ███ individuals, it must be culled immediately. Any SCP-511-1 found outside the containment site shall be euthanized and the remains incinerated.
Any biological material leaving the containment site for testing will be handled in accordance with standard protocols for a level 4 biohazard. All specimens are incinerated after testing is complete. Before coming in contact with any material from the containment site, personnel must be inoculated for Influenza, Hepatitis A, Hepatitis B, ████████ █, Tetanus, Tick-borne encephalitis, and ███████ ██████. Full medical workups are mandatory on a bi-weekly basis for personnel working with SCP-511.
Instances of SCP-511 typically occur within residential structures with a block or stone foundation that includes a basement or crawlspace. All attempts to remove an instance of SCP-511 from such a residence have proved ineffective. (Ref: Interview 511-A)
SCP-511 is always found associated with a colony of feral Felis domesticus, common domestic cats. Members of this colony are designated SCP-511-1.
SCP-511 is a mass of biological matter taking the form of a large feline, often with extra limbs, eyes, mouths or other organs. It is typically coated with dirt, blood and fecal matter, making its fur appear black despite its actual coloring. (Tests have shown SCP-511’s fur to actually be a random patchwork of various feline coat patterns, colors, and lengths.) SCP-511’s mass varies from 10kg to over 50kg, roughly in proportion to the number of SCP-511-1 in the associated colony. The tissue that makes up this mass consists primarily of the bodies of deceased SCP-511-1. The portion of SCP-511 that does not comprise SCP-511-1 consists of other biomass; small rodents, various plant materials, insects and insect larvae, black mold, a human [DATA EXPUNGED]. Incorporation of dead tissue into SCP-511 does not appear to slow the normal process of decay. Different areas of SCP-511 undergo different stages of biodegradation at any given time; some areas show little more than lividity, while other areas may show active carrion insect infestation, and some areas may even show liquefaction of tissues. (Note: Researchers have described SCP-511 making a “purring” sound. Tests have shown this sound does not originate with SCP-511, but is actually the sound of insects, most often blowflies, trapped within its mass— Dr. A. ████)
SCP-511 prefers to inhabit dark spaces with a relatively high humidity, such as old basements and crawl spaces. It will continually scavenge its immediate area for new biomass to incorporate into itself, displacing and expelling matter that has decayed past mechanical usefulness.
Examples of SCP-511-1 resemble ordinary Felis domesticus that have undergone extreme neglect. They display a body condition score of 2 or 1, regardless of the amount of food available. Ulcerated skin is common, as are parasitic infestations, tumors, and various viral and bacterial infections. (SCP-511-1 are known carriers of a particularly virulent strain of ███████ ██████.) A typical SCP-511-1 shows no interest in grooming itself, and has patchy and matted fur. It is unclear to what extent the physical condition of an SCP-511-1 is a result of the influence of SCP-511, and to what extent it is due to sub-optimal living conditions.
Several observations have been made of an SCP-511-1 retrieving biomass from elsewhere and bringing it to SCP-511 to be incorporated.