I think you're reaching on this one. Doesn't look like anything out of the ordinary to me. Especially given the distance and angle. Angles and shadows often have a way of creating hard lines that can be perceived as something it really isn't. Plus, the picture is blurry (as they always are) and this can be deceiving as well. There's always stuff like this in nature. Objects that resemble familiar objects or shapes to us and we perceive them as something they are not. The brain wants to do this at all times. I bet if you were standing right next to it you would suddenly find yourself laughing at how wrong you really were and how it is rather ordinary. There's flat lines all over that photo. You just happened to key into the closest thing in your vision.

Sorry, but this is not an unidentified object. Just a rock with some sheer angles, which is pretty damn common.