Bacteria often do not separate and adhere to each other after asexual reproduction (fission). The greatest variety of arrangement occurs in the cocci; and spiral shaped bacteria rarely remain attached. Bacteria are often singles; but pairs (diplo); chains (strepto), irregular clumps (staphylo), and cubicle clumps (sarcina) do occur. Since bacilli divide primarily in only one plane, it is possible to have a hinged end where cells snap back upon each other forming side by side arrangement called palisade. Corynebacterium (causes diptheria) often appears like an irregular picket fence following the snapping that happens when the bacterium divides during fission.

Small bacteria like the cocci range from 0.5-3 microns in diameter; bacilli range from 0.5-20 microns; and spirals range from 0.5-200 microns. Since many bacteria have similar sizes, it is sometimes difficult to correctly identify the shapes of bacteria. Use the Internet or a microbiology textbook to identify the shape and arrangement of Clostridium, E.coli, Flavobacterium, Enterococcus, Sarcina, Mycobacterium, Pseudomonas, Proteus, Borrelia, Francisella, and Rhodospirillum. Yeast and worm eggs are not bacteria, but what shape best describes yeast and worm eggs?