Purple polyps

Acropora is a genus of hard coral including more than a hundred species, some known as elkhorn or staghorn corals for the antlerlike texture of their multitudinous polyps. Acropora species' tough exoskeletons and fast growth are critical to living reef structures across the globe, with Acropora found in the Pacific and Indian oceans as well as the Caribbean. While these carapaced Cnidarians come in a seemingly endless palette of colors, purple specimens like this are considered quite rare.