“Negotiating Boundaries” Is a regenerative design approach and material innovation (Seacrete) that promotes eco-friendly building material derived from seashells. This innovation is crafted for architects, urban planners, and advocates who recognize that human survival depends on coexisting with nonhuman life. By sharing materials with natural ecosystems, Seacrete enriches marine habitats as it dissolves, fostering biodiversity and circular, life-supporting cycles. Embracing erosion and sea-level rise, this project demonstrates that thriving means designing for all species, not just our own.