Red algae

Red algae are members of the phylum Rhodophyta. This is a large group of aquatic algae with about 6000 species. They have reddish phycobilin pigments—phycoerythrin and phycocyanin. 
The red algae are a distinct group. They have eukaryotic cells without flagella and centrioles. Their chloroplasts lack external endoplasmic reticulum. These chloroplasts have unstacked (stroma) thylakoids. 
Phycobiliproteins are accessory pigments, which give them their red color. What these pigments do is the same as what chlorophyll does: absorb sunlight as energy, which is then used to fuel the building of organic compounds.
Red algae store sugars as a type of starch outside their plastids. 
Most red algae are multicellular, macroscopic, marine, and reproduce sexually. The usual red algal life history is an alternation of generations with three generations rather than two.
Chloroplasts evolved following an endosymbiotic event between an ancestral, photosynthetic cyanobacterium and an early eukarytoic phagotroph.
Most species grow near tropical and subtropical shores below the low-tide mark. A few are found in fresh water. Red algae is used to make the food "Nori".