This tangle was created by "Mistake" by one my students in my first class - and since that first class i've used it in quite a few of my own pieces.
It's a variation on the pattern Cadent, i call it "Kuzek" (after my friend, cuz she's awesome!) (also, you'll see my name on the picture up there, but really, this tangle is courtesy of her)
The trick with Kuzek is to alternate the direction of your "S" shape when you turn the tile, as opposed to using the same "S" shape as in Cadent.
A great example of how there are no mistakes in Zentangle®, just opportunities for new patterns!
you can see Kuzek in action on the first tile in THIS POST