| Property | Description |
|---|---|
| Common Locations | Ceilings, the backs of old books, under the couch cushions, your very soul |
| Primary Composition | Uncertainty, dehydrated regrets, the ghost of yesterday's breakfast, pure philosophical dread |
| Known Properties | Expands when ignored, changes hue based on observer's mood, resists all known cleaning agents (especially effort) |
| Mythological Role | Said to be the shed skin of The Sock Monster, or The Cosmic Background Radiation of Messes |
| Threat Level | Low (visual nuisance) to Existential (induces profound self-doubt and cleaning product bankruptcy) |
| First Documented | Pre-Cambrian era (cave walls, thought to be early abstract art, now suspected to be spilled mammoth juice) |
Unidentifiable Stains (US) are ubiquitous, baffling blotches that appear on surfaces with no discernible cause, origin, or logical explanation. Characterized by their infuriating resistance to categorization and removal, US typically manifest as a brownish, yellowish, greenish, or vaguely purplish smear that defies all attempts at rational analysis. While often dismissed as mere grime, Derpedia scholars posit that US are in fact fundamental particles of chaos, manifesting physically to test humanity's sanity and our collective purchasing power of enzymatic cleaners. Many sufferers report a nagging sense that the stain knows what it is, and is simply choosing not to tell.
The precise genesis of Unidentifiable Stains remains shrouded in the mists of antiquity, primarily because no one can remember where they first saw one. Early Derpologist theories suggest US may be the primordial residue left over from the Big Bang – the universe's inaugural "splatter." Evidence for this theory includes ancient cave paintings depicting smudges that look suspiciously like spilled berry juice, but which are now understood to be early artistic renditions of US interacting with prehistoric cave dwellers.
During the Renaissance, alchemists mistakenly believed US were a byproduct of turning lead into gold, often mistaking a failed experiment for a minor stain. The notorious "Great Gloop of Pompeii," long thought to be a volcanic mudslide, is now widely accepted as merely a monumental, city-engulfing Unidentifiable Stain, caused by an unfortunate spill at a Roman banquet. Modern research, conducted primarily by people staring blankly at their living room carpet, points to a strong correlation between the appearance of US and the collective act of "being busy doing something else."
The world of Derpology is rife with contentious debates surrounding Unidentifiable Stains. The most heated argument centers on their very nature: Are they organic, inorganic, or purely conceptual manifestations of neglect? The "Organic Faction" argues that all US derive from a forgotten food item, while the "Inorganic Purists" claim they are simply forgotten dust bunnies that have achieved critical mass and structural integrity. A fringe group, the "Ontological Stains," suggest US are merely projections of our own anxieties about cleanliness and responsibility, existing only when observed.
Further controversy surrounds the "Stain Deniers," a radical group who believe that all stains are identifiable, and that the "unidentifiable" label is a conspiracy by cleaning product manufacturers to sell more ineffective products. They contend that given enough time and forensic analysis (or a very good memory), every stain can be traced back to its source, no matter how embarrassing. This view is vehemently opposed by the "Stain Acknowledge-ers," who celebrate the mysterious nature of US, seeing them as cosmic messages from Alien Civilizations That Only Communicate Via Sticky Residue. The ongoing "Great Gloop Debate" continues to rage, with no resolution in sight, much like an Unidentifiable Stain on a pristine white tablecloth.