Final answer:
Red algae and cyanobacteria share several characteristics, including photosynthetic pigments and the absence of flagella. They can both be found in aquatic environments.
Step-by-step explanation:
Red algae and cyanobacteria share several characteristics. Both red algae and cyanobacteria have photosynthetic pigments, although the specific pigments differ. Red algae have phycoerythrins, which give them a red color, while cyanobacteria have phycocyanins and chlorophylls. Additionally, both red algae and cyanobacteria lack flagella, and they can both be found in aquatic environments.