Bacteria come in many sizes, shapes and structures but their rigid cell walls maintain their definite shape. Some examples of bacterial shapes are seen in the image below.

A poster dividing bacteria into three morphological categories; cocci, bacilli and others. Cocci are cells which are shaped as spheres. Cocci can be found as single cells called coccus, two cells bonded together, called diplococci, many cells connected in long string like pearls, called streptococci or many cells clustered together, called staphylococci. Bacilli cells which are rod-shaped and can be found as single cells with many tail-like structures attached at one end of the cell, two cells bonded together, called diplobacilli or many cells connected in chain-like structure, called streptobacilli. Other morphologies include cock-screw shaped bacteria, called spirochete, single cell rod-shaped bacteria with one tail-like structure, called vibrio or cock-screw shaped bacteria with many tail-like structures attached at one end of the cell, called Spirilla.

Figure 1: Bacterial Morphology: Example of bacterial morphologies.