Black on Concrete Wall (Photo) What is this?

Could be whatever they were using to break the bond between the forms and the concrete.

I agree with Jayrod

Is this a party wall? If it is a basement, was the basement where the photo was taken, an addition? Could it be the remains of Asphalt/Bitumen waterproofing?

Can you determine how the wall was constructed? Maybe it was cast in a trench, and the black is residual material, or even bentonite or similar. That would explain the texture, which does not appear to be formed.

There is a pattern, but I don't know what signifies. Every 6 ft or so there is a vertical tray of little circles, spaced maybe 1 ft apart (almost look like rebar form savers for a wall). At the bottom of each of these arrays is a single large circle. In one case that single circle appears to be an open-ended pipe, but the others appear to be capped?