Originally Posted by ZombieBreath
I have a theory about this.....
When you "dig" the invisible mob on the ground you don't defeat it. You do make it move to a new random location, but its not defeated. When you "dig" the mob numbers pop up showing damage like a normal mob, and I've even 2 hit combo'd the ground before by getting the dig spot right away again. I believe that each maps dig spot is one spot that has a set amount of HP and "runs" when you dig it, and that in order to get anything from the ground you have to "defeat" the dig spot.
Just my thoughts anyway what do you think?
That theory might work (and take down the theory I have), but it's hard to tell whether the spot you hit is the first attack, in the middle of being damaged, or nearly dead; I'm saying that it's difficult to tell when the cycle restarts and how much damage it takes before finally exploding in a spectacular (yet invisible) way and dropping an item. The JP LaTale wiki had a theory of an excavation mob having only 10HP, but it didn't seem right (it was crossed out). It might actually be a variable, but it's not like we'll get any hints from the big guys.
That was a mouthful, but you get the gist of it, right?