Multicellular Multicellular green algae are made up of many cells. The cells often combine together to form a macroscopic organism. Chara is an example of a multicelular green algae. The members of the phylum Chrysophyta are unique because they produce a carbohydrate called chrysolaminarin. One of the principle groups of this phylum are the diatoms.
Diatoms are unicellular photosynthetic organisms.
They are encased in a double shell made up of opaline silica. Their shape and size vary immensely. One example is shown below. The euglenophyta are in their own phylum due to their unique characteristics. They have a flagella, but some have chloroplasts and are autotrophic.