CAN ANYONE SOLVE THE MYSTERY?

This interesting fragment of stone bears the inscription "DAVID LEWIS 1679". It was found in the churchyard of the Catholic Church in Usk but no one seems to know anything about its history. Knowledge of its age, origin, etc, seems to be lost in the mists of time. The stone, which has a small cross embedded in it, appears to be the remains of some sort of memorial to the martyred Welsh Jesuit. This stone may or may not be of any significance but, since the only purpose of this blog is to make St David Lewis better known, anything that has even a remote connection to our wonderful Saint is worth investigating, in so far as we are able. Not being professional historians or archaeologists, we are at a decided disadvantage. However, we are devoted to St David Lewis so we do our best with our limited talents. Whatever this curious artifact is, it must have a story and, important or not, it would be nice to know that story. Therefore, I am asking if anyone out there in Blog land has any knowledge of this object? I would be more than delighted to hear from you if you do. (FOR A BETTER VIEW OF THE STONE, CLICK ON THE PICTURE TO ENLARGE IT.)