I have a house that was built in 1860. The kitchen addition is 1930-1940. The walls are covered in a type of paneling. The bottom is green with a fake tile design. Looks like tiles with grouting. The top is smooth. I once tried to pound a nail with a hammer into the wall and had no luck. It took an impact drill to hand a picture. I was wondering if anyone knows what type of wall covering this is and how to care for it. Thanks for any insight! Lenore New Hampshire