Step 1: Understand the question.
A one-dimensional (1D) nanostructure is tiny in two directions but long in one direction, like a thin wire. We must find which choice is NOT 1D.
Step 2: Recall the dimension types.
A 0D structure is small in all three directions, like a tiny ball. A 1D structure is long and thin, like a rod or tube.
Step 3: Check nanowires and nanotubes.
Nanowires are long and thin, and nanotubes are long hollow cylinders. Both are clearly 1D.
Step 4: Check fibres.
Fibres are also long and thin, so they count as 1D.
Step 5: Check nano shells.
Nano shells are hollow round shells. They are small in all directions, so they are not 1D.
Step 6: Choose the answer.
The one that is NOT 1D is nano shells, which is option 1.
\[ \boxed{\text{Nano shells}} \]