What are the common features of multicellular algae?

All algae are autotrophic protozoa. As the simplest, algae often have complex cellular structures. For example, algal cells can have one or more chloroplasts, which contain structures called pyrenoids that are capable of synthesizing and storing starch. Chloroplasts themselves differ in the number of membranes, which indicates secondary or rare tertiary endosymbiotic relationships. Algae do not have real tissues or organs like plants. In addition, seaweed does not have a waxy cuticle to prevent drying out.