What are algae? A simple, non-flowering, and typically aquatic plant of a large group that includes the seaweeds and many single-celled forms. Algae contain chlorophyll but lack true stems, roots, leaves, and vascular tissue. Singular: Alga Plural: Algae What are Omega-3 Fatty Acids? Algae Omega-3 Algae based omega-3 is suitable for vegans and vegetarians people.