The discovery of natural slab photonic crystals in diatoms has sparked questions regarding their prevalence and functional role in nature. These advanced nanomaterials open so-called photonic stopbands in two dimensions, enabling precise light manipulation essential in technologies like quantum computing and photonics. However, the natural role of these advanced properties remains a mystery. In this study, we adopted a multidisciplinary approach, combining taxonomic, evolutionary, and photonic property analyses. Using scanning electron micrographs, we examined the girdle elements of the silicon dioxide shell from several hundred diatom species to explore the potential correlation between occurrence of slab photonic crystals and taxonomic relationship. Girdle slab photonic crystals emerged among the oldest diatom classes, with stopband properties covering the visible to mid-infrared spectral range. Square lattice formations emerged first, evolving from quasi-ordered templates, and later diverged into more efficiently packed hexagonal structures. This study shows how photonic nanomaterials developed from quasi order to order over evolutionary trajectories and provides a sustainable inventory of natural slab photonic crystals for application and deeper investigation. Understanding how diatoms utilize these structures can inspire innovative principles for smarter energy management systems as well serve as a model for the evolution of order and symmetry in cellular processes and organization.