Phrikoceros katoiis commonly referred to as Kato’s Flatworm, Polyclad Flatworm.
Little flatworms are active and fast-moving, often ruffling out from one crevice to another among coral rubble. They may even swim for a short distance with vigorous ripples of their body edges. Swim using waves of motion, even Harlequin Sweetlips juveniles mimic this motion to avoid predation.
Flatworms are primitive as they were one of the first species to evolve after the cnidarians. When they are in season, some may be seen stranded on the sand. Please watch your step!