Complex sentence: The convex polyhedron representing an Apollonian network is s a 3-dimensional stacked polytope, a polyhedron that can be formed starting from a triangular face by gluing additional tetrahedra one at a time onto its triangular faces.
Split into simpler sentences: The convex polyhedron representing an Apollonian network is s a 3-dimensional stacked polytope. Such a polytope can be obtained from a tetrahedron by repeatedly gluing additional tetrahedra one at a time onto its triangular faces.