These are photosynthetic microalgae that have an outer cell wall made of silica in an intricate overlapping soap-box-like manner. They belong to the class Bacillariophyceae.
Diatoms are found in both marine and freshwater environments.
Advantages:
They are photosynthetic and are the primary producers in the ocean and support large strata of consumers in the food chain.
They also increase the amount of dissolved oxygen through photosynthesis and provide nutrients in the water.
When the diatoms die, their silica-based shell covers the ocean floor forming diatomaceous earth.
This diatomaceous earth is soft and porous and is used in various industries like oil refineries.