Apparatus and a method for establishing a cellular mobile call. The disk drive system is comprised of a rotatably mounted magnetic disk. The side walls have a curved shape, whose convexity is oriented towards the outside of the implant; the intermediate wall has a curved shape, whose convexity is oriented towards the outside of the implant such that it does not form any pronounced angles with the supporting side walls. When formulated into pellets, the disclosed animal feeds have excellent durability, such that pellet fracture and dust formation are minimized.