I am not saying that it isn't a BB, They tend to reserve the designation for coins that are MS, as Nickel is fairly easy to tone dark or black.
Hard to know for sure due to the circulation of the coin, but it looks like a circ. 'black beauty' to me.
Thank you! I did keep it. I also put it in a 2x2 Labeled. . After seeing so many Nickels, my gut feeling went towards a BB