The Great Barrier Reef is one of the world’s natural wonders, covering an area larger than Italy and drawing nearly 2 million tourists every year to boat, swim, snorkel and dive amid its elaborate flora and fauna. It generates some $6 billion in revenue for Australia annually and provides employment to more than 50,000 people. It’s also one of the planet’s most fragile ecosystems, home to more than 11,000 species that live, if not necessarily in harmony, in a carefully orchestrated symbiotic balance. At the foundation of this giant ecological and commercial enterprise is one tiny marine organism: the