This is the "Ufer", the electrical ground connected to rebar, that should have been in the foundation, but neither the engineer nor concrete guys mentioned it, so..... had to dig & pour a 12"x12" x 22 foot chunk of concrete. Curiously enough, "ufer" is not an acronym - it is named after a guy named Ufer who invented this method of grounding for the army in WW2.

Below are some shots of plumbing roughed in by Mel of Double Diamond Plumbing.