Rhodophyta, or red algae are a type of macroalgae found deep within the oceans. They produce phycoerythrin, a pigment that absorbs blue light and reflects red light. This is what helps them to photosynthesize and survive deeper in the ocean. Rhodophyta is used in Asian cuisine, such as nori, for human consumption. Each serving contains a high amount of protein and vitamins, and humans have been eating this seaweed for hundreds of years.