There it is, a couple inches above the tip of the stake.  Just the tip of a tooth, sticking out from the packed silt.  The question is, "How big is it?"  It could be half an inch.  It could be 3 inches.  There's no way to tell at this point (no pun intended).  Because the tooth may be fragile, you need to be careful.  It's best to undermine the tooth by digging below it (as I've started to do, in the picture).  Next, dig an inch or two away on both sides.  Click the tooth to dig a little more.