The metal detector found this piece, there is more that we couldn't get dislodged from a root running through the ground where we were prompted to dig. We thought it was likely part of an old iron fence or wheel, but after washing the dirt off we aren't so sure. It's got a little weight to it, but seems like it might be part of a rib cage, from what creature in what era we haven't a clue. We were, as usual, digging by the creek under the bridge at the foot of the cliffs in Carversville, Pa, with a metal detector that we were using for the first time. Between our proximity to the bridge and it being our first time out with the detector, I'm not confident that it was these pieces setting off the machine. We are going back to dig up the rest of the pieces in the morning so will post more pics tomorrow if needed for further clarity.