A scientific cross-section illustration of a purple sea urchin (Paracentrotus lividus) test revealing intricate calcareous ossicle plate architecture, tubercles for spine attachment, membrane分布, and internal lantern jaw (Aristotle's lantern) structure on aged cream paper, handwritten Latin annotations describing each echinoderm adaptation and feeding mechanism, measurement scale in centimeters along the edge, soft aquarium filtered light from upper left casting delicate shadows, museum archive quality, Pantone-accurate deep violet test with olive green spine bases and ivory Aristotle's lantern highlights, composition dynamic to showcase the sea urchin's ancient radial symmetry architecture, mood: marine precision capturing echinoderm wonder, hyperrealistic details of ossicle texture and spine socket patterns visible