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.