At this point I stopped and said, "Limey, is that a rock or an animal?" We both squinted for awhile and when dd2 suddenly stopped within a couple of feet of it, I yelled at her to back away.
We had to walk right next to the porcupine to continue down the path. I was pretty close when I took this photo.
After we passed, it turned around and moved very slowly away. The porcupine was definitely the highlight of our day.