Swimming Rhodobacter sphaeroides
This organism has one flagellar filament that emerges from the side of the cell body. When the filament spins (usually clockwise), it is helical and the cell runs. When the filament stops, it coils up and the cell stops. The coiling tends to reorient the cell body.
Armitage, J.P. and Schmitt, R. Bacterial chemotaxis: Rhodobacter spheroides and Sinorhizobium meliloti -- variations on a theme? Microbiology 143, 3671-3682 (1997).