In a sample of pond water, a new organism is identified with the following characteristics: It consists of 70 cells surrounded by rigid cell walls, which join the cells together. Inside each of these identical cells are mitochondria and chloroplasts. Such an organism would most likely be classified as a
colonial photosynthetic eukaryote

Colonial protists are individual protists that form a colony and act as a larger, multicellular organism. This colony may consist of many individual protists of the same species, but what's really cool about them is that instead of acting as individuals they work together to function as one large group, benefiting from each other
Most protists are unicellular, but some like kelp is multicellular organisms. Some, known as the plant-like protists photosynthesize, while others that do not photosynthesize are called animal-like protists. Others still are called fungi-like or slime molds because they somewhat resemble fungi, though again there is no evolutionary relationship