Read the following paragraph and select the most important supporting detail. Take an animal the size of a pencil eraser. Combine it with millions of plantlike creatures called algae, which live in the animal's body. You get a coral polyp. Corals are animals that can also act like plants. That's how they became the master builders of almost 3,000 coral reefs that make up the Great Barrier Reef. Corals are animals that can also act like plants. You get a coral polyp. Combine it with millions of plantlike creatures called algae, which live in the animal's body: Take an animal the size of a pencil eraser. That's how they became the master builders of almost 3,000 coral reefs that make up the Great Barrier Reef.