Figure 1.

(a) Optical microscopy images of Coscinodiscus sp. (b) Simplified 3D structure of the unit cell of diatom frustule based on experimental results. Thickness of the three layers: Cribellum t₁ = 50 nm, Cribrum t₂ = 300 nm, Internal Plate t₃ = 1000 nm, (c) Left: top view of cribellum, the lattice constant p₁ = 200 nm and the hole size d₁ = 50 nm. Middle: top view of cribrum, the lattice constant p₂ = 400 nm and the hole size d₂ = 250 nm. Right: top view of internal plate, the lattice constant p₃ = 2 μm and the hole size d₃ = 1.3 μm.