What Are Corals? Objective Students will be able to: 1. Define the vocabulary term coral. 2. Identify and explain the role of corals in American Samoa's marine ecosystem. 3. Understand that corals are living animals. Background Corals consist of small, colonial, plankton-eating invertebrate animals called polyps, which are anemone-like. Although corals are mistaken for non-living things, they are live animals. Corals are considered living animals because they fit into the five criteria that define them (1. Multicellular; 2. Consumes other organisms for food; 3. Has an internal digestive system Duration: 60 Minutes.