Several novel morphologies of "crew-cut" aggregates have been prepared from highly asymmetric diblock copolymers of polystyrene-b-poly(ethylene oxide) (PS-b-PEO) and polystyrene-b-poly(acrylic acid) (PS-b-PAA) in dilute solution. The morphologies include simple, circular, and interconnected tubules, large compound rods, a structure of interconnected bicontinuous rods, branched short rods, spheres with protruding rods, and porous spheres, as well as aggregates containing combined morphologies. Some of these structures are biomimetic. Branched abort rods and spheres with protruding rods appear to be intermediate structures trapped during morphological transitions. This study illustrates the high degree of kinetic control which can be exercised over the morphologies of molecular self-assembled nanostructures. Some of the aggregates may have potential applications in areas such as separations and drug delivery systems.