Polyp, a tiny sea animal, introduces Atoll, a mineral, and Algae, a plant. Animal, Mineral, and Plant are coral. They are ancient sea life--older than dinosaurs. Their partnership is explored while they thrive in a sunny place underwater. When Greenhouse Effect warms the air and ocean Polyp and Algae separate due to a warmer sea. Coral bleaches. The La Niña weather pattern brings cooler temperatures and a new friendship with Alga that revives Polyp and the reef. Notes explain the importance of coral reefs to ocean and land life, ocean science, and how our weather is affected by sea life. This picture book is intended for Middle-Grade Readers.