What characteristic is notable about carbon nanotubes' structure?

Carbon nanotubes are notable for their unique structure, which contributes to their exceptional electrical conductivity. The cylindrical shape of these nanotubes allows for the delocalization of electrons along their length, which is a key factor in their ability to conduct electricity. This property makes carbon nanotubes particularly useful in a variety of applications, including in electronics, where they can be utilized for transistors, sensors, and other components.

In terms of their structure, carbon nanotubes are not hollow spheres as that would imply a different geometry. They are also not rigid and brittle; instead, they exhibit remarkable strength while maintaining flexibility. Lastly, while they are composed of carbon atoms, they do not consist of only one type of carbon atom in terms of bonding; the carbon atoms form strong covalent bonds in a hexagonal lattice, contributing to their unique properties. This intricate arrangement is what underpins their distinctive characteristics, including their impressive electrical conductivity.