One group of ubiquitous microscopic organisms with a siliceous cell wall demonstrating structural diversity in morphology, are diatoms. Complex 3D nano and micro-scale silica structures produced by the frustule might be highly significant in the nanotechnological field. Advancement in studies of diatoms include application of electron microscopy (SEM), which allows the profound examination and detailed study of structures at different magnifications. In the present work, ultrastructural characterization and morphological features of diatoms as revealed through scanning electron microscope were described. This investigation in the form SEM micrographs will serve as a guide to morphological diversity of diatoms.