This is a photograph of dog feces. The feces is covered in various unicellular bacterial organisms. A unicellular organism is an organism that is quite simply made up of only one cell. Prokaryotes and protists are unicellular. Bacteria are prokaryotes. Prokaryotes divide by binary fission. Binary fission is a form of asexual reproduction in which a cell copies its DNA and then attaches either copy to a different side of cell membrane. Both cells produced are identical to each other and to their mother cell.