“Underwater pastures, / ancient as dinosaurs, / vital as trees, / filled with wonders,” Schaub writes as she tantalizingly beckons young audiences to join the racially diverse set of young snorkelers and beachcombers in Le’s flowing marine scenes. Slipping in explanatory notes between lines of sonorous free verse, the author begins by differentiating seagrass—flowering plants that evolved from land plants millions of years ago—from both terrestrial grasses and seaweed. Along with pointing to the expansive “medley of marine life” that lives in these shallow water “meadows,” from anemones and seahorses to dugongs, she describes how the plants, as “lungs of the sea,” supply oxygen while slowing global warming by absorbing carbon dioxide, filter out floating plastic and other pollution, and in many places serve as part of a complex ecosystem with adjacent coral reefs and mangrove forests. Schaub closes with an invitation to readers to join the “seagrass heroes” who are working, directly or indirectly, to clean up and preserve these vital natural resources. Small photos enhance the appended glossary, and annotations to an added gallery of close-up portraits by the illustrator supply further detail on the realistically rendered, appealingly posed sea creatures glimpsed clinging to or hiding among waving green fronds in earlier views throughout.