Bought a short block pulled from a 98 LS, got it stripped down to the bare block. What you see in the pics is what I saw inside the crank case next to one of the cylinders... what is it?

Before bake parts cleaner:



After some brake parts cleaner and wiping off:

 

can we get a pic of the location from further back?

 

Inside the crank case


Here's the spot, my finger is pointing right at it. It's the area right next to the cylinder.

 

it looks like a casting flaw but i would get it tested just to make sure its doesnt go farther then the surface