Corals Are Animals, Not Plants

Coral stays in one place and can look like a rock or a plant, which is why the question comes up. NOAA’s National Ocean Service answers it directly: corals are sessile animals, meaning animals that stay fixed in place. They take root on the ocean floor, but they are not plants. What we call a coral is usually a crowd. NOAA explains that most coral structures are made up of hundreds to thousands of tiny coral creatures called polyps. Each soft-bodied polyp, most no thicker than a nickel, secretes a hard outer skeleton of limestone, or calcium carbonate. Plants do come into the story. NOAA says coral relies on its relationship with plant-like algae to build the largest structures of biological origin on Earth.