Optical microscopic images of diatom cells cultured on four types of SAM surfaces. (A), (E): FPS. (B), (F): OTC. (C), (G): CMS. (D), (H): APS. (A) to (D): unrinsed. (E) to (H): rinsed after one day of incubation. The incubation period was 40 days. Horizontal size of the images is 5.3 μm.