The sansnombredroze makes its home in horizontally-aligned drainage pipes, particularly those that cut through parks or other outdoor, grassy areas. During ebbs in the water flow of these pipes, it spills forth from the walls as a clear liquid, first pooling, then rising with a swell. It coagulates into solidity from the tail-tip forward, its mask growing with an abrupt stab, thus marking the sansnombredroze's maturation. The sansnombredroze displays some initial discomfort towards its mask, either scratching where the plastic connects to the skin, or attempting to readjust via pushing turns, but appears to grow comfortable within the half-day.

The perseverant sansnombredroze spends its life on the move through the pipe system in which it appears, establishing a territory early on. It buckles its legs close to its body as it travels through these channels, moving in a serpentine matter and shedding a layer of mucus that that further aids in locomotion. Unable to drown, it is equally adept underwater, with its mouth releasing a steady stream of oxygen bubbles when submerged.

Upon reaching the end of its linear path, the sansnombredroze doubles back on itself and reverses its direction until reaching the opposite bound.

When it does cross paths with another of its strain, each allows the other through without incident or further interaction, compressing against the walls when needed. No sansnombredroze shares a complete path with any other sansnombredroze.

When the sansnombredroze's path reaches an opening through which it can emerge into a verdurous exterior space (for example, a small park or other plot of wooded land), it slips from its path and steps onto the ground with a gristly pop, shedding its mucosal layer as it does so. The sansnombredroze appears relieved by these periodic breaks, and upon full emergence from its pipe, engages in an exaggerated and soundless pantomime of breathing, its sides raising and falling in rapid swells and its neck widening as though taking in large inhalations.

Following this display of exhaustion, its demeanor becomes more relaxed, and it spends the next 10-14 minutes at rest. During these periods of respite, the sansnombredroze grows talkative, muttering to itself with a distracted calmness. It also engages in a wide range of actions specific to its environment; it may pluck a flower with idle curiosity, run its hands up and down a tree trunk, or try to bite at a sign, its hard face unable to allow it to grip. It seems distracted and distanced in these actions, however, as though its mind is elsewhere.

When the sansnombredroze first encounters a sensitive, it is timid, but curious, moving forward with small steps, but keeping its distance. Sudden movements cause it to step backwards (and occasionally desist in its curiosity altogether), although the sansnombredroze does not display a panicked or hurried response.

If a sensitive attacks the stranger, that sansnombredroze will avoid all sensitives from that point on. If its flesh is pierced, the sansnombredroze's pearlescent, rubicund inner fluid becomes watery and spills from the wound; depending on the size of the wound, this can spill out at a constant dribble to a slopping gush. The sansnombredroze cannot heal itself on its own; instead, when injured, it returns to its pipes and scrapes dried mucus from the walls, grinding this mineral-like substance into its flesh, an action which facilitates regeneration.

After five minutes, the sansnombredroze's presence causes a sensitive to feel uncomfortable with the idea of exposing their face. A sensitive feels as embarrassed and horrified by the thought of their face being seen as other individuals would feel when made nude in front of a crowd. A sensitive thus become overcome by a compulsion to craft a mask suitable of covering such nudity; this incessant urge brings with it an incredible amount of creativity and ingenuity as the affected individual gathers any suitable materials from their surroundings, all craftsmanship and problem-solving beyond what might be otherwise expected in such a panicked state. A sensitive will not feel compelled to cause damage to their own face, however, and will avoid creating masks which cause injury.

The eyes are allowed to remain uncovered, as are the ears, sides of the head, jawline, and chin.

The sansnombredroze's effect, profound as it may be, lasts only for twelve minutes; as such, not all masks are able to be finished, with the compulsion dissipating as quickly as it arose.

As the sansnombredroze ages, it displays increasing discomfort at its mask, stopping with escalating frequency to first pat at its face, then claw at the skin around the mask in an attempt to pry it off. It becomes vicious and territorial during these bouts of malaise, slashing at any beings that interrupt its self-dividing. As it struggles, its injuries grow more severe, until the sansnombredroze collapses. Its corpse becomes a flesh that rots into plastic-scented water, while its mask persists. This mask remains indestructible during the first ten days following the stranger's death, but becomes fragile once this time has elapsed, crumbling apart into a dust that can color the skin, and time scatters to nothing.

A sansnombredroze that encounters one of its companions' masks picks it up and aligns it over its own face for 6.8 seconds before placing it on the ground, snout-up. Each time this occurs, it doubles the duration of this sansnombredroze's effect upon a sensitive, as well as the ferocity of its own eventual death throes.