The rod is a ubiquitous shape adopted by walled cells
from diverse organisms ranging from bacteria to fungi to
plants. Although rod-like shapes are found in cells of
vastly different sizes and are constructed by diverse
mechanisms, the geometric similarities among these
shapes across kingdoms suggest that there are common
evolutionary advantages, which may result from simple
physical principles in combination with chemical and
physiological constraints. Here, we review mechanisms of
constructing rod-shaped cells and the bases of different
biophysical models of morphogenesis, comparing and
contrasting model organisms in different kingdoms. We
then speculate on possible advantages of the rod shape,
and suggest strategies for elucidating the relative
importance of each of these advantages.