It started with a glass octopus. Dusty, broken, and all but forgotten, it caught Drew Harvell’s eye. Fashioned in intricate detail by the father-son glassmaking team of Leopold and Rudolf Blaschka, the octopus belonged to a menagerie of unusual marine creatures that had been packed away for decades in a storage unit. More than 150 years earlier, the Blaschkas had been captivated by marine invertebrates and spun their likenesses into glass, documenting the life of oceans untouched by climate change and human impacts. Inspired by the Blaschkas’ uncanny replicas, Harvell set out in search of their living counterparts. In A Sea of Glass, she recounts this journey of a lifetime, taking readers along as she dives beneath the ocean's surface to a rarely seen world, revealing the surprising and unusual biology of some of the most ancient animals on the tree of life. On the way, we glimpse a century of change in our ocean ecosystems and learn which of the living matches for the Blaschkas’ creations are, indeed, as fragile as glass.