I like Steph's definition for a snake but even the use of auger is somewhat messed up by some. I think of auger as a drill bit and, to me, ideally the ribbons should not reach the edge of the marble. However many do and I can see that. But then, you look down the middle of the drill bit, from top to bottom, and you should not see a "hole" in the middle. But, again, some have a small hole and are still called augers. Here's an example of an auger, pictures by marblealan that is a lazy one so....?