Mid-poly celestial nautilus: 20-ft-diameter pearlescent shell with shifting pink-violet-teal cosmic swirls and soft electric-blue glow at aperture. Body emerges with long sinuous tentacles covered in luminescent suckers pulsing from cold white to cobalt. Head translucent with star-like speckles, glossy black eyes. Shell surface weathered by barnacles and drift kelp strands. Materials: nacre sheen, subtle surface scratches, water droplets; fine PBR and displacement maps. Neutral coiled pose with tentacles gently splayed, ensuring proper IK deformation zones. Clean quad topology, game-ready mid-poly, 4K textures (albedo, normal, roughness, metallic, AO).