Please help identify my mysterious rock.?

I pretty much agree with Busterwasmycat. Definitely not a meteorite, although I can see how it could be confused. Other than being chert, the only other possibility would be a fine grained limestone. If you could put a drop of pool acid (muriatic acid - a weak hydrochloric solution) on it, it would bubble. If it does not, it is most likely chert. (By the way, good photography. I see lots of out of focus shots on Yahoo Answers.)