With an estimated 20 percent of the world’s coral reefs already destroyed, the hidden cup coral faces many threats that are affecting coral reefs globally (6) (7). Worldwide there is increasing pressure on coastal resources resulting from human population growth and technological development. Consequently, there has been a significant increase in domestic and agricultural waste in the oceans, poor land-use practices that result in an increase in sediment running on to the reefs, and over-fishing, which can have ‘knock-on’ effects on the reef (6). However, the major threat to corals is global climate change, with the expected rise in ocean temperatures increasing the risk of coral ‘bleaching’, in which the stressed coral expels its zooxanthellae, often resulting in the death of the coral. Although, the hidden cup coral is an azooxanthellate coral, and does not suffer from ‘bleaching’, subtle changes to the reef ecosystem are likely to impact on this species. Climate change may also lead to more frequent, severe storms, which can damage reefs, and rising carbon dioxide levels may make the ocean increasingly acidic. Such stresses can also make corals more susceptible to disease, parasites and predators, such as the crown of thorns sea star (Acanthaster planci) (6) (7) (8).