Slab photonic crystals – nanoscale structures that enable fast communication, sensing, and quantum logic – are typically engineered in cleanrooms. However, nature has already mastered this technology in the silicon dioxide shells of diatoms. In a study published in Scientific Reports, researchers from MP2Lab, in collaboration with the University of Texas, the University of Alabama (USA), and the Institute of Optics (Spain), investigated the evolutionary trajectory of these natural photonic crystals. Our findings reveal that these structures emerged early in diatoms and later diversified into distinct forms, covering the visible and near-infrared spectrum. Remarkably, once established within a genetic lineage, slab photonic crystals remained as irreversible functional traits. Understanding how diatoms use these advanced photonic properties in their biology could inspire smarter energy management technologies while offering insights into the evolution of symmetry and order in biological systems.