Any Geoligests here

Seriously though. Where was it found?
It does not appear to be meteoric.
It does not appear to be a coprolite.
It does not appear to be petrified wood or grained organic mateial.
It is not fossilized bone.

Could you post some close up pictures that are not so blurry?
Take a piece of sand paper and smooth a location on it and take pictures of that spot and post them.
Also, sand the part that is harder than the rest. The ring looking part, not the indention part.

I feel it is limestone and is probably part of an ancient sea bed.

Location location location. More info needed.