The Octahedron is an intertidal coastal armoring unit designed to be used in conjunction with or in lieu of conventional rock rip-rap. Unlike conventional rock rip-rap, these Octahedron units are designed with a complex interiority that attracts a range of coastal bivalve species and crustaceans. The complex interiority reduces heat stress and desiccation of organisms while providing refuge areas from predation. The irregular octahedron shape allows the units to next comfortably in existing rip-rap and perform ecologically in any orientation.