Paramecium bursaria, light microscope footage. This ciliate protozoan has a symbiotic relationship with a green alga called Zoochlorella. The algae live inside the Paramecium in its cytoplasm and provide it with food, while the Paramecium provides the alga with movement and protection. Paramecium bursaria is the only species of Paramecium that forms symbiotic relationships with algae, and it is often used in biology classrooms both as an example of a protozoan and as an example of symbiosis.