Is this a rock?

[BLT]

Could anyone tell me if this is some type of fossil, bone or rock? I found it in a creek in middle Tennessee. Thanks! 

[Kane]

I'm seeing some texture in the second image in the middle of the more circular area. Could you do a closeup of that? At the moment, it looks a bit like a coral (such as Hexagonaria).

[ynot]

I will side with a non fossil rock on this piece.

[BLT]

Thanks, @Kane, @ynot. Here are a few close up pics. 

[Kane]

Thanks for the closeups.  Hm. I am now doubting my initial coral guess, and may be leaning more to ynot's assessment that this may just be a worn sedimentary rock. 

[BLT]

Thanks so much! @Kane

[ynot]

I stick with My original assessment, non fossil rock.

[Rockwood]

Standing on their own rocks like this may look as if they formed in some weird hard to imagine way, but inclusions like this which are more durable than the country rock are actually quite common. 

[BLT]

Thanks again, @ynot! Thank you, @Rockwood! I have recently found four rocks similar to this shape. 

[ynot]

All look the same to Me, concretions in sandstone.

Often porous rock will have areas within it where minerals have concreted which makes that area of the rock a little harder and more resistant to erosion.

[GeschWhat]

51 minutes ago, BLT said:

Thanks again, @ynot! Thank you, @Rockwood! I have recently found four rocks similar to this shape. 

Not seeing fossils either, but they are really interesting and fun!

[BLT]

Thanks, @GeschWhat! Can anyone tell me what caused this oddly shaped rock to form this way? 

[ynot]

Looks like two layers of differing rock where one has eroded more than the other.

[BLT]

Thanks, @ynot!

[Rockwood]

It may have been a corner that broke off in between larger blocks of the lighter colored rocks that just happened to stay with the layer above or beneath it.

[abyssunder]

There might be ichnofabrics and trace fossils in your specimens, but it's hard to say, also there is the possibility of geological creations, as Tony suggested.

[BLT]

Thanks!