What kind of rock is it in? Could it have been dropped by someone a long time ago, and then some form of natural concrete hardened around it? It might not be a forgery, it could have just been misidentified by Creationists who don't know much about geology to begin with.
I think that this is the most likely case here.
What I would be interesting in understanding better is whether this is a matter of incompetence or dishonesty.
The finding should be subject to very careful analysis. (It should, of course, had it's providence carefully recorded too - that is lost through carelessness now).
It would seem that this has almost certainly not been done. Perhaps because those with it don't understand what is necessary to get a better answer. The other explanation is that they know perfectly well what they have (or rather don't have) and don't want it carefully analyzed.