Deep-sea corals are colonies of small animals that share a skeleton. What are these organisms called?

• A. Seagrass
• B. Sponge
• C. Anemone
• D. Coral

Answer: (D)

Deep-sea corals show how many tiny animals can join together to form one hard, shared skeleton. They’re corals, a type of cnidarian related to jellyfish and sea anemones, living as many small polyps that secrete calcium carbonate to build a single, continuous skeleton. That shared skeleton creates the big, reef-like structures you find in the deep sea. Seagrass is a marine plant, not an animal with a skeleton. Sponges have their own skeletal elements but don’t form a single shared skeleton the way corals do, and anemones have soft bodies and don’t create a calcium carbonate skeleton as a colony. So, the described organisms are corals.