Single-celled algae. Scanning electron micrograph (SEM) of Ulkenia sp., a single-celled marine organism from the family Thraustochytriaceae. This microorganism can be used to prepare lipids that contain docosahexaenoic acid (DHA), a non-essential omega-3 fatty acid. The process entails cultivating the algae in a medium and recovering the lipids from the culture. Magnification: x1700 when printed 10 centimetres wide.