Red Sea Reef Colours A | B | C | D supplements contain the 31 minor and trace elements present in the skeleton and soft tissue of all corals. The elements in each supplement are related by their biological function and are associated with the production of specific colour pigments (Pink, Red, Green/Yellow and Purple/Blue) in the soft tissue of stony corals. All 31 elements are required by all stony corals irrespective of the actual colour the coral displays.