The one I've seen has a lobe at the top and a sort of slot for the signal connectors. It's unlike any I'd seen before.
Nikon are not alone in using pointlessly annoying non-standard USB's one of my Olympus cameras is (but the other isn't !) and I've seen weird Sony, Pentax, Kodak and Canon connectors.
Just part of their pension plan in case you lose the one that came in the pack.