How do you go about finding a mate if you can't go and look for one? This is the problem corals, which are rooted to the seabed, have found a spectacular way to solve - mass spawning. But how do they make sure they all do it at the same time? And what happens after all the eggs and sperm are released into the water? In this Special podcast, Sarah Castor-Perry finds the answers to these questions and more from James Guest of the National University of Singapore.