This mysterious thing, which at first glance seemed straight out of a Star Trek episode, is actually a 2004 mirror artpiece called Superficial by French artist Michel de Broin:
Upon invitation to reflect on the notion of transparency, that led me into the forest to envelop the contour of a large stone with fragments of mirror. The large stone, tucked away deep in the woods, became a reflective surface for its surroundings. In this play of splintered radiance, the rock disappears in its reflections. Because it reflects one cannot be mislead by its presence, yet we cannot seize it, rather it is the rock that reflects us.