Red algae are a group of marine plants known for their reddish color, which comes from pigments called phycoerythrins. They primarily thrive in warm, shallow waters and can often be found in coral reefs. Red algae play a crucial role in marine ecosystems, providing habitat and food for various marine organisms. These algae are also important for humans, as they are used in food products like nori, which wraps sushi, and in thickening agents like agar. Additionally, red algae contribute to the production of oxygen and help in carbon fixation, supporting overall ocean health.