Mysterious Cthylla, underwater queen, dark blue skin, glowing bioluminescent markings, long curly black hair, piercing green eyes, intricate shell necklace, flowing seaweed-inspired dress, majestic fins, sitting on an ancient coral throne, surrounded by schools of iridescent fish, soft glowing jellyfish lanterns, dimly lit abyssal cavern, eerie ambient lighting, cinematic composition, 3D rendering.