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 be found in various ocean environments, from coral reefs to rocky shores. Red algae play a crucial role in marine ecosystems, providing habitat and food for many marine organisms. These algae are also important for human use. They are harvested for their nutritional value and are commonly used in food products like nori, which is used to wrap sushi. Additionally, red algae are a source of agar and carrageenan, substances used as thickening agents in various food and cosmetic products.