The Kingdom Protista includes a diversity or organisms. What unites these various organisms in the Kingdom Protista is that almost all are unicellular. Included among the plant-like members of the Kingdom Protista are diatoms. The image shows a single living diatom photographed with high power of a research microscope. The diatoms are quite unusual in the living world because they have cell walls made of glass.
Diatoms are present in great abundance in most aquatic ecosystems.
When marine diatoms die and settle to the bottom, they form massive deposits. These deposits are called diatomaceous earth. This rock-like material is used in filters, such as swimming pool filters, in polishes, and in the paint used for highway stripes. The cell walls of many individual microscopic diatoms are shown in this image. Algae are photosynthetic and live in an aquatic environment.