Kristen Marhaver studies coral, tiny creatures the size of a poppyseed that, over hundreds of slow years, create beautiful, life-sustaining ocean structures hundreds of miles long. As she admits, it's easy to get sad about the state of coral reefs; they're in the news lately because of how quickly they're bleaching, dying and turning to slime. But the good news is that we're learning more and more about these amazing marine invertebrates — including how to help them (and help them help us). This biologist and TED Senior Fellow offers a glimpse into the wonderful and mysterious lives of these hard-working and fragile creatures.