Brian Cox and Robin Ince are joined on stage by Marcus Brigstocke, and marine biologists Prof Callum Roberts and Dr Heather Koldewey as they look at the amazing creatures that create and colonise coral reefs. Just 2 microscopic organisms are responsible for the creation of these incredible structures, structures so huge that they can be seen from outer-space. Brian, Robin and the panel talk about the vital yet delicate relationship between the coral polyp and and its tiny plant lodger, how they evolved to be so co-dependent, and how this unique partnership has lead to some of the most diverse ecosystems on the planet. They also look at the very real threat to our planets reefs as our oceans warm, and what, if anything can be done.