From the fiercest predator to the lowliest plant, every member of an ecosystem is immeasurably important to the survival of their environment. Although they're not regarded as a keystone species, sea urchins play a pivotal role in maintaining healthy marine environments. Without sea urchins to consume algae, entire coral reef ecosystems could collapse. This educational text invites readers to imagine a world without sea urchins, delving into curricular science concepts, such as interdependence of species, with accessible language and real-world examples.