I would assume that your gecko ate it's tail.... although I've never had that happen with one eating it's own tail, it's certainly not uncommon for a cage mate to eat one for a snack.

By the way, NP means: No Post.
Generally used to write a message in the title of a post, without actually posting inside the title. In my opinion, a complete waste of time and a post. Why not just write the comment in the post? If your response is not worth a post, just one sentence, then it is not worthy of responding. Just my opinion