Corals rely on their single-cell symbionts, Symbiodinium, for photosynthesis. Despite this vital symbiotic relationship, little is known about how Symbiodinium move and find their coral hosts. Here, 200 frames of a video (taken at 50 frames per second) of swimming Symbiodinium was collapsed into a single image. Swimming trajectories in tight circles (dark donuts) and helical patterns (dark wavy lines) are observed. It remains a mystery why circular trajectories, with little to no horizontal displacement, are favored by so many cells. My research goal is to elucidate the chemical cues that allow Symbiodinium to find their coral hosts.