Shapes of bacteria:
Bacteria can be divided into four types based on the shape
Coccus - About spherical and always non-flagellate. They can be Monococcus ( occur singly), Diplococcus ( occur in pairs), Streptococcus ( occur in chains), Staphylococcus ( irregular clusters), Sarcina ( geometrical forms) etc.
Spirillum - Coiled forms giving the spiral appearance. Eg. Spirillum minus
Bacillus - Rod-shaped with rounded or blunt ends. E.g. Monobacillus, Diplobacillus etc.
Vibrio - Little less than one complete twist or turn resembles comma (,). E.g. Vibrio cholerae