Here is nutritional yeast (Saccharomyces cerevisiae) in water. This yeast is round to egg shaped, 5 to 10 micrometers in diameter. Nutritional yeast is a form of Saccharomyces cerevisiae that has been killed with heat. The same species of yeast has been used since the dawn of civilization for baking, brewing, and winemaking.
Equipment used: AmScope M150C microscope at 400x magnification