Revolver cylinder mark?

[Jeepguy1002]

To me this looks like a revolver cylinder. It is on a large flat slab on the ground. Any other ideas as to what it is or was used for? It has a piece of metal in the middle.

 

[Mark60]

Not sure for what purpose, star alignment?, but those holes have been cut really clean

 

[In Deep]

Looks like core samples
Some university's drill into rock to age it

 

[A2coins]

Core samples