A mysterious epidemic has wiped out billions of sea stars in recent years. A new study finally identifies the bacterium responsible.

With the sharp decline in sea stars, the sea urchins that usually serve as a food source rapidly expanded in population. In turn, they ate nearly 95% of the kelp forests in Northern California within a decade. These kelp forests help provide food and habitats for a wide variety of marine life, including fish, sea otters and seals, per the AP.