Post-Apocalyptic Monster in a Ruined Basement

A realistic post-apocalyptic predator creature adapted to abandoned cities, quadrupedal but capable of briefly standing upright, elongated muscular body, long forelimbs, low stalking posture. Dark skin covered in a light-absorbing organic biofilm, wet and matte texture, fungal-organic appearance. Narrow elongated head with minimal facial features, small or absent eyes, sensory cavities instead of eyes, flexible jaw with multiple rows of backward-curving teeth. Long prehensile tail, arched back with subtle organic ridges. Set inside a dark ruined city basement, broken concrete, roots and humidity, cinematic lighting, horror atmosphere, ultra-detailed, realistic anatomy, dark tones.