Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons, fans, zigzags, or stellate colonies.
Colored scanning electron micrograph (SEM) of squamous cell carcinoma (cancer) cells from a human mouth. The many blebs (lumps) and microvilli (small projections) on the cells' surfaces are typical of cancer cells.
These cells line the Choroid Plexus, a layer of tissue that lines the inside of the ventricles of the nervous system. The swollen tips of these cells secrete the cerebrospinal fluid which bathes the brain in glucose and proteins, and prevents it from collapsing under its own weight.