Unicellular prokaryotes are commonly referred to as bacteria. These organisms are characterized by their single-cell structure and lack of a nucleus and other membrane-bound organelles.
Bacteria can be found in a variety of environments, from extreme heat to icy conditions, and they play crucial roles in ecosystems, including nutrient cycling and decomposition. The simplicity of their cellular structure allows them to reproduce quickly, adapt to various conditions, and sometimes even develop resistance to antibiotics.