Bacilli are rod-shaped prokaryotes. They are one of the three basic shapes of prokaryotes, along with cocci (spherical) and spirilla (spiral). Bacilli are typically found in soil, water, and the human body. Some common examples of bacilli include:

* Escherichia coli (E. coli)

* Bacillus subtilis

* Pseudomonas aeruginosa

* Streptococcus pneumoniae

* Staphylococcus aureus

Bacilli can be either Gram-positive or Gram-negative. Gram-positive bacilli have a thick cell wall made of peptidoglycan, while Gram-negative bacilli have a thin cell wall made of lipopolysaccharides.