It's based on Euglena gracilis, single cell algae that move in response to changes in strong light. (phys.org)
In one study, Ono et al. (2010) compared the effects of concentric leg curls with 50 % of 1RM with eccentric leg curls with 120 % of 1RM on gracilis EMG amplitude but found no differences between conditions. (strengthandconditioningresearch.com)
The modified procedure uses gracilis muscles from the thigh placed in two directions and sometimes three placed at the corner of the mouth or the upper lip to the cheek and eyelid to recreate an authentic smile that shows teeth and gum on both sides of the face. (sciencedaily.com)