Spirillum is a genus of bacteria characterized by its spiral shape. These bacteria are typically found in aquatic environments, such as freshwater and marine habitats. Spirillum species are known for their unique flagella, which allow them to move in a corkscrew motion, aiding in their mobility through water. Some species of Spirillum are aerobic, meaning they require oxygen for growth, while others can survive in low-oxygen conditions. They play a role in the ecosystem by contributing to the decomposition of organic matter and can also be involved in nitrogen fixation, which is essential for soil health.