Algae is called a eukaryotic organism that has a nucleus (single or multiple nuclei) and it also photosynthesizes like plants but it lacks the reproductive structure like stems, roots, leaves, etc. Algae and Bacteria are both microorganisms and they both photosynthesize as well. They are both crucial elements in the food chain. While Algae Fuels the ecosystem by being part of the aquatic food chain,  bacteria break down dead matter and make it part of the soil.