A prismatic-fossil-deer with a skeleton of translucent amber-bone interlocking segments and antlers of cascading geode-crystal formations, standing in a vast underground crystal cavern where rainbow light refracts through mineral-veined walls and pools of still mercury reflect fractured prisms overhead, scientific field notes cross-section mapping crystallizing bone-tissue networks and light-absorbing crystal lattice systems, palette of geode purple, amber gold, mercury silver and pale rainbow spectrum, Victorian natural history speleological expedition illustration aesthetic with detailed geological annotation callouts and crosshatched mineral vein shading