Looked at some brood comb with rock hard black cells today. Used an open paper clip to check consistency, its what I had on me. They're hard enough to bend it. Looks like the cells have been filled with hard black propolis, no brood in them.
Lots a of bee bread, cells back filled with honey not capped, appears to have swarmed and queenless, has scattered capped brood in two boxes, some on the verge of emerging. nothing runny, two queen cells in the standard brown brood comb color. in two different boxes.
My first thought is it's simply old comb, but would like to double check with you all here.