I'd always theorized on that, but I'd never managed to test it before today.
(I mean, it makes sense. (-1)^2 is 1, and (-1)^3 is -1, and what happens between that? It's certainly not going to approach 0. It only makes sense for || (-1)^x || == 1 for all values of x, therefore a corkscrew is the only possible shape. QED.)