The study investigates the mechanical protection provided by the silica shells (frustules) of diatoms, which are crucial components of phytoplankton blooms in aquatic ecosystems. The authors used real and virtual loading tests, including finite element analysis, to measure the strength of centric and pennate diatom cells. They found that diatom frustules are remarkably strong due to their architecture and the material properties of diatom silica. The results suggest that diatom frustules have evolved as effective mechanical protection, requiring exceptional force to break them. This defense mechanism likely influences the evolutionary arms race between diatoms and their predators, shaping pelagic food webs and biogeochemical cycles. The study also highlights the structural complexity and stability of diatom frustules, which resemble sophisticated man-made constructions. The findings provide insights into the ecological factors that drive the species composition of diatom blooms and their role in the ocean's biological carbon pump.The study investigates the mechanical protection provided by the silica shells (frustules) of diatoms, which are crucial components of phytoplankton blooms in aquatic ecosystems. The authors used real and virtual loading tests, including finite element analysis, to measure the strength of centric and pennate diatom cells. They found that diatom frustules are remarkably strong due to their architecture and the material properties of diatom silica. The results suggest that diatom frustules have evolved as effective mechanical protection, requiring exceptional force to break them. This defense mechanism likely influences the evolutionary arms race between diatoms and their predators, shaping pelagic food webs and biogeochemical cycles. The study also highlights the structural complexity and stability of diatom frustules, which resemble sophisticated man-made constructions. The findings provide insights into the ecological factors that drive the species composition of diatom blooms and their role in the ocean's biological carbon pump.