Op, have you ever been in an area where basalt columns are found? Before they break off and appear to be singular columns, they are a solid mass. If you could look down on this mass from the top, it would look similar to honey comb, dark, solid honeycomb. These columns are like a huge, solid, rather crystaline mass.

You should visit an area where they occur, and examine them. Hundreds of square miles of solid basalt is awesome.

Living among basalt formations and observing it in such an enormous scale lead me to believe that it isn't likely to have been created by man.