Flattened carbon nanoshells,carbon nanorods, and nanostructures of rod-tube have been observed in the cathodic doposits produced by a double-anode arc-discharge. As confirmed by high resolution transmission electron microscope (HRTEM), the growth of a carbon nanotube was directly linked to the nanorod, so the origin and development of nanotube seed is clearly discernible. In addition, the multishelled carbon nanorods HRTEM images revealed an isolated center line. We consider that such a line is probably a linear acetylenic carbon allotrope based on “sp” hybridization containing triple and single bonds.