Tetrajack pile

These are 4" new-age brick prototypes to be for construction of earthquake-resistant housing in the middle east.  The shape is deceptively simple:  there is an equilateral tetrahedron "inside" the form with 4 more tetrahedrons mounted on the 4 faces of the base tetrahedron.  This photo shows these shapes as if they were poured out of a bucket.  No attempt was made to pack them closely together.  Under the right circumstances, very accurate renditions of this shape will pack together until there is less than 10% void space between them - unprecedented for a shape with such pronounced features.