The Monera Kingdom, now largely outdated in modern taxonomy, traditionally included unicellular organisms like bacteria and cyanobacteria. These prokaryotic organisms lack a true nucleus and membrane-bound organelles.
While the Monera Kingdom is no longer used in current biological classifications, it played a historical role in organizing the study of unicellular life before the advent of the three-domain system.
Cyanobacteria, also known as blue-green algae, contribute to oxygen production through photosynthesis.
