A detailed characterization, using high resolution electron microscopy/microanalysis (SEM, TEM, HRTEM, and EDX), reveals tubular carbon nanostructures exhibiting complex and fascinating morphologies. The materials were obtained by sulfur-assisted chemical vapor deposition. It is demonstrated that S not only acts on the catalyst, but also can be detected in the carbon lattice of the nanostructures. The experimental data presented here confirms the critical role of S, which is responsible for inducing curvature and therefore influencing the final carbon nanostructure morphology. In particular, different types of covalent Y-junctions of CNTs and even sea urchin-like nanostructures were produced and their experimental conditions are listed and discussed.