The Bivalve Hypar Concrete Shell explores a cast concrete structure that mediates between New York City’s urban edge and its tidal ecosystems. Formed as a bivalved shell with a hypar perimeter, it fits irregular riprap shorelines and embeds cavities for oysters, mussels, and bladderwrack to promote filtration, habitat stability, and biodiversity. The shell was cast using a woven surface within a hypar pneumatic frame, enabling efficient formation of complex curvature with minimal waste. This fabrication method integrates ecological function directly into the structure, offering a scalable model for restoring marine habitat along urban shorelines.