Living Forest. Go to the section after the Brotherhood Of Shadow. Long Jump across the gap with the tiny waterfall. Go through the door. Now, get the Clay Statues to come to life. Destroy their shield. You only need 1 of them. Now, get one of them over near the Giant Stone Cloumn on the other side of the stream. It's the stone column right near where you entered. Throw the Clay Statue into it! It should come crashing down. Now, return to where the little waterfall was. There is no longer a waterfall. Just a Koin that contains Reptile.