Scleractinia

• Refertina
• Acrosmiliidae
• Actinacididae
• Actinastreidae
• Agatheliidae
• Agathiphylliidae
• Amphiastraeidae
• Amphiastreidae
• Andemantastraeidae
• Aphyllacis
• Aplocoenia
• Archaeosmiliidae
• Elkhorn coral Acropora palmata

  These branching structures belong to an animal, not a plant. Elkhorn coral grows in shallow Caribbean waters; thickets shelter fish and other creatures.