Polarized light micrograph of a Paramecium bursaria (left) and a Monommata sp. rotifer. Paramecium bursaria are ciliate protozoans that share a symbiotic relationship with the small green algae Zoochlorella. Rotifers are common in freshwater environments. They use their cilia (microscopic hairs) and two toe-like projections for locomotion. Magnification: x330 when printed 10 centimeters wide.