What is the name given to spiral-shaped bacteria?

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Spiral-shaped bacteria are called spirilla. They appear as rigid, helical rods, which sets them apart from cocci (spherical), bacilli (rod-shaped), and vibrios (curved, comma-like rods). Note that spirochetes are also spiral but are more tightly coiled and flexible, a different category from spirilla. The singular form is spirillum, and spirilla is the plural.