North America’s native, freshwater mussels were once so abundant they paved river bottoms. But now, after more than a century of overharvesting, competition from invasives, pollution, climate change, and other threats, native mussels are experiencing an apocalypse, according to National Geographic.

This episode of Sprouts features citizen scientists who have fought to protect and preserve our most endangered fauna while government agencies have lacked the will or resources to do so.