These sketches show the diversity of form and shape found in coral reefs but they can't do justice to the color palette encountered by poking your nose (or goggles) between these staghorns. It is a pity to think that warming waters are endangering these vital ecosystems. Corals have a very limited temperature range within which the xooanthellae, the algae that live in the coral casing and provide nutrients to the coral polyps, can live. When the algae die-off, the coral is not far behind. To make matters worse, the excess man-made CO2 in our atmosphere enters the ocean through absorption by phytoplanktonic photosynthesis. It is this CO2 that is acidifying the ocean waters and making carbonic acid that weakens shellfish and the coral structures. The beautiful array of marine life that live in the reefs are in danger of losing their homes if fossil fuel emissions are not reduced and CO2 levels in the atmosphere brought back to 350 ppm.