I am assuming, like in Kakhitt, you mutate the starting organism.
This is Trichobala tribozahexasomata. Like its predecessor, a cell buds off the main organism to becoming another full multicellular organism, which separates from the parent organism. Also, it can undergo sexual reproduction.
It has tri-symmetry, where each side of the triangular multicellular organism is made of two individual cells. The apical surface, the outside, is the one made of the flagella pointing out. There is currently nothing on the lumen surface, or inside, yet. Since the organism is slightly smaller, it is also slightly faster in moving than its predecessor.
Each cell has also mutated a way to make ATP from light using a light-induced proton pump called Proteorhodopsin. Obviously, there are more Proteorhodopsins in each cell than what can be drawn. Thus, Trichobala tribozahexasomata gets extra ATP during the day.
