1. Myth: Moriah’s scar comes from his fight with Kaido.
Fact: The origins of Moriah’s scar have not been revealed. Those scars have existed for at least 20 years though as shown in the chapter 0 (and appears to have grown over the years). Though it appears on the skin, it is also unconfirmed to be a scar, since almost all other scars seen with stitches in the series have normal “-” across them. For a surgeon, an “x” scar would make the skin close incorrectly on the wound, disputing the pressure on the closed wound incorrectly. This is why surgeons always do a straight stitch across as it pulls the flesh together equally.
2. Myth: That’s not a scar! He is wearing a mask!
Fact: Note worthy enough, the “scar” has lengthened over the years. But even before Chapter 0 was released, this theory cropped up on his face being a mask or based on a mask. To date, this is also unknown and one can presume as far as the readers are concerned that it is his true face. Early concept arts of Moriah shown him to be wearing a mask. However, the mask theory is debunked when it is revealed on the latest SBS where Oda draw the Shichibukai as children, Moriah’s face was in fact the same in his childhood, though a bit skinnier. He also does not seem to gain his scar and stitches on his face yet.