Which of the following describes the three common shapes of bacteria?

The common shapes of bacteria are indeed described as round, spiral, and rod. These classifications are based on the physical morphology of bacterial cells. Round bacteria are referred to as cocci, spiral bacteria as spirilla or spirochetes, and rod-shaped bacteria as bacilli. This classification is crucial in microbiology, as the shape can influence the bacteria's metabolic capabilities, their movement, and how they interact with their environment and hosts. Understanding these different shapes also has practical implications for lab identification and the treatment of bacterial infections, as certain shapes may be associated with specific types of diseases or pathogenicity. The other options present shapes that do not accurately represent the established categories recognized in the study of bacteria.