Abstract: Structural cells that are placed beneath hardscape. The cells are strong enough to structurally support the hardscape, effectively bearing its weight along with the weight of any load it carries. Furthermore, even though the cells are strong enough to offer structural support of a hardscape, the cells are also designed to be relatively lightweight, stackable, and open, allowing approximately 90% of their volume, or more, to be free volume that can contain uncompacted soil, tree roots, and the like. The cells achieve these attributes through a design that includes a flexible bottom frame, and support members. These support members have a cross-sectional shape that allows for axial rigidity while also preventing any interlocking between support members when cells are stacked. In one embodiment, this cross-sectional shape is a generally quadrifoil shape.