Phytoplankton, or vegetable plankton, is composed of unicellular and multicellular algae, alone or in colonies.
Cymbella = 0.07 mm
Algae come in a wide variety of forms: they can be star-shaped, round or filamentous.
Cosmarium = 0.04 to 0.2 mm
This is a microscopic view of the green alga Cosmarium.
Saint-François Bay
They can be of microscopic size or grow up to several metres long.