Prokaryotes without nuclei in algae, such as cyanobacteria (no more common examples), are unicellular algae, without macroalgae, and they are all individuals that can only be seen under a microscope.

Some unicellular algae and macroalgae are eukaryotes, such as green algae, red algae and brown algae. Common examples are kelp, Nostoc flagelliforme and seaweed.