Eleven years ago, a mysterious disease killed most of the adult starfish off California and Oregon. The most severely affected, Sunflower Seastar, was the main predator limiting the spread of Purple Urchins. The sudden disappearance of a key predator triggered a "trophic cascade" that led to an ongoing ecological crisis, including the collapse of the kelp forests. After a decade of painstaking research, the pathogen responsible for Seastar Wasting Disease has finally been identified.