A spherical container having a shell formed by 6 bands, interwoven in such a way as to create 12 pentagonal openings spaced evenly around the sphere. Modification of the membranes to generate charge includes modification of membrane pores to alter charge within a pore and alter the size of a pore. In an exemplary embodiment, a bone anchor assembly is provided that includes a bone anchor configured to engage bone, a receiver member for seating a head of the bone anchor, and a compression member for securing the bone anchor at fixed angle with respect to the receiver member when the compression member is seated within the receiver member. Examples of the cost include cost for size of required storage area, and cost for required operation of CPU.