Subject: What is the difference between a rock and a fossilized bone?

I have found several rocks that look pieces of bone on my property. The shape 
of some look like leg or arm sections (thinner mid-section and thicker at the 
end). These bones have a smooth texture unlike the rougher rocks that are more 
common here. Given my geographic location (north Georgia), is it possible that 
these could be fossilized bones? 

Re: What is the difference between a rock and a fossilized bone?