An implant for the closing of defect openings in the body of a human or animal is proposed, with a load-bearing structure which, in a first operating state (primary form), has a great ratio of length to transverse extent along an axis (9) and, at least in a further operating state (secondary form), has a much smaller ratio of length to transverse extent along the axis (9), the load-bearing structure (1) being capable of being reversibly transformed from the secondary form into the primary form by exertion of a force against elastic material forces, the secondary form assuming approximately the form of a double disc with a proximal disc element (7) and a distal disc element (6) for receiving the surroundings of the defect opening between the disc elements, and the load-bearing structure (1) being formed essentially in one piece without joining connections, and a placement system.