nautilus shell 3d model

"Create a hollow nautilus shell-inspired form for a passive mobile phone amplifier. The object should be made of realistic polished stone and measure exactly 30 cm in height, 24 cm in maximum width, and 17 cm in depth. The front opening at the end of the spiral is a perfect circle with a 17 cm diameter. There should be no holes, slots, or features on the shell body except for a single slot on the top, measuring 10 cm long, 5 cm wide, and 5 cm deep, used for partially inserting a mobile phone vertically. The shell's wall thickness must be 1.5–2 cm, and the inner cavity is completely hollow. The spiral proportions must match a logarithmic nautilus reference, with smooth stone texture and continuous curvature. Do not add any legs, base, or extra appendages—only the shell form itself with the specified top slot. Present a half-front (three-quarters) view render; emphasize accurate stone material and precise, production-ready geometry."