a ply for a paper and paperboard made from a ply substrate material , wherein the ply comprises a hybrid material , in an amount of 1 - 25 wt -% of the ply , wherein the hybrid material is introduced into a target suspension of the short circulation of a fibrous web forming process of a fibrous web machine , in an in - line process , wherein said target suspension forms the ply substrate material , and the hybrid material comprises an alkaline earth carbonate precipitated onto or into fibers or fibrils of a nanofibrillated polysaccharide .