A dog
What they all thought was a beaver was finally pulled out of the mud. Everyone broke out in applause and was happy that they managed to help this poor animal and save its life. But then they looked closer at it and realized that their beaver was actually a dog.
Not only a dog but an injured one, that had something wrong with one of its legs. It was at this moment that Jim put the pieces of the puzzle together in his mind. He knew what happened and shared his insight with the rest of the rescue team who were still confused.