This illustration depicts a diatom, specifically a pennate diatom, which is a type of unicellular microalgae belonging to the class Bacillariophyta. The image focuses on the diatom's frustule, which is composed of silica. The shape of this diatom suggests it belongs to the pennate category, characterized by its elongated structure. Diatoms are significant primary producers in both marine and freshwater ecosystems and play a crucial role in photosynthesis and biomineralization processes. The predominant colors in the illustration are grey and white.