Bacteria have a unique shape that likely only evolved once. This shape is the a. coccus. b. diplococcus. c. spirochete. d. bacillus.

a. coccus

Explanation:

Coccus refer to a spherically shaped bacterium. Their shape can only be determined by the use of a microscope. When coccus bacteria reproduce, they give rise to other patterns. Types of coccus bacteria include staphylococcus, enterococcus, streptococcus.

The coccus bacteria cause about one third of bacterial illnesses. They can also be classified according to their different reaction to gram stain, that is gram positive and gram negative.