Vertically aligned carbon nanotube arrays
In materials science, vertically aligned carbon nanotube arrays (VANTAs) are a unique microstructure consisting of carbon nanotubes oriented with their longitudinal axis perpendicular to a substrate surface. These VANTAs effectively preserve and often accentuate the unique anisotropic properties of individual carbon nanotubes and possess a morphology that may be precisely controlled.
Source: Wikipedia — Vertically aligned carbon nanotube arrays (CC BY-SA 4.0)