The Archaean classification covers single celled organisms up until the evolution of plants and animals (algae, sponges and plankton). Most such worlds will be full of metazoan life in the form of bacteria, and is named after the Archaean period on Earth. It may last around a billion years.
The success of bacteria can prevent the evolution of more complex life. Anaerobic bacteria initially prevent the build up of oxygen in the oceans.
Archaean worlds contain life, but it is very simple.
It inherits the basic non-living material from which life is formed, which are found in large quantities on Organic worlds:
The exact path that evolution takes on each world is different, but there are certain stages which are passed through from simple to more complex life forms.