A prismatic cave-peacock spider with iridescent crystalline scales covering its compact arachnid body, each scale refracting rainbow light like fractured gems, perched on a glowing selenite crystal cluster in an underground luminescent lake cavern, surrounded by glowing milky quartz formations and dangling gypsum needle crystals, scientific field notes cross-section mapping light-refracting scale structures and silk-producing spinnerets, palette of deep obsidian black, phosphorescent rose quartz, crystalline diamond white and soft aurora rainbow, Victorian natural history scientific expedition illustration aesthetic