Characterized by an elongated, robust body that can reach lengths of 75 to 120 millimeters when fully extended. The base coloration of this terrestrial gastropod ranges from yellowish-gray to olive-green, adorned with a mottled pattern of pale yellow spots distributed irregularly across the mantle and back. The mucus secreted when the animal is handled or disturbed is exceptionally thick, sticky, and possesses a diagnostic bright yellow color, whereas the pedal mucus used for locomotion is typically colorless. The ocular tentacles are distinctive, exhibiting a striking bluish-gray hue. The dorsal keel is relatively short and confined strictly to the posterior section of the body tail.

Geographical distribution: Native to Southern and Western Europe, particularly around the Mediterranean basin and the British Isles. However, due to human activities, international trade, and the transport of horticultural goods, it has achieved a cosmopolitan distribution. Currently, it is widely established in North America, major parts of South America (including Argentina, Brazil, Chile, and Uruguay), as well as Australia, New Zealand, South Africa, and several temperate regions of Asia.

Habitat: Strongly associated with anthropogenic environments, frequently categorized as a synanthropic species. It is commonly found in damp basements, cellars, greenhouses, domestic gardens, old stone walls, compost heaps, and underneath decaying wood or bricks. It requires microenvironments with high relative humidity and complete protection from direct sunlight to prevent lethal desiccation, leading it to seek deep, dark crevices during daylight hours.

Feeding: Predominantly detritivorous and mycophagous in its dietary habits. The primary food sources consist of decaying organic matter, fungi, lichens, molds, and decomposing plant material. Unlike other invasive gastropods, it rarely inflicts severe damage on living crops or ornamental plants, preferring to scavenge on kitchen scraps, moist pet food left outdoors, and rotting garden refuse, utilizing its powerful radula to scrape surfaces.

Behavior: Exhibits strictly nocturnal activity patterns to minimize cutaneous water loss. It is a solitary creature that emerges from its hiding spots only after dusk, displaying a sophisticated homing behavior that allows it to return to the exact same shelter morning after morning. When threatened or physically disturbed, it contracts its body into a compact, semi-spherical shape and releases a copious amount of its characteristic sticky yellow mucus as a chemical defense mechanism against predators.

Reproduction: Functioning as a simultaneous hermaphrodite, each individual possesses both male and female reproductive organs capable of producing gametes. Courtship takes place during humid nights, involving a circular trail-following ritual followed by a reciprocal transfer of sperm. Following successful copulation, individuals deposit clutches of 10 to 40 translucent, oval eggs in moist, dark crevices, beneath rotting logs, or deep within soil cracks. The juveniles hatch after several weeks, appearing as miniature versions of the mature adults.

Conservation status: Currently listed as Not Evaluated on the IUCN Red List, as it is a highly resilient and common species with an expanding global range. In many regions where it has been introduced, it is classified as an introduced exotic species with low to moderate ecological impact, rarely outcompeting native mollusks or disrupting local ecosystems to a critical degree.