Scientific cross-section illustration of a sea urchin test (Paracentrotus lividus) revealing intricate calcareous plate architecture with ambulacral and interambulacral arrangement, tube foot muscle channels, digestive tract distribution, and Aristotle's lantern feeding apparatus on aged cream paper, handwritten Latin annotations describing each echinoderm skeletal adaptation and ray-based locomotion mechanism, measurement scale in centimeters along the edge, soft marine laboratory spotlight from upper left casting delicate shadows, museum archive quality, Pantone-accurate deep olive-green spine bases with amber-yellow test plate highlights and cream tube foot channel accents, composition dynamically centered to showcase the echinoderm's 200-million-year-old marine evolution, mood: zoological precision capturing spiny invertebrate wonder, hyperrealistic details of plate suture patterns and lantern jaw muscle distribution visible