[ The view is rather eerie in the dusty light, but he's seen worse, on men with skin as plain as his own. Those teeth are the most threatening thing about the view, but it's nothing to the mess that gnashed in his face the first day he came. He does not look away, though he tilts his head back to inspect with his pale eyes.
The next motion is purely for his own sake, a thumb that reaches up to curiously chase the line of one of those peculiar flaps of skin. If the stranger's intention had been to perform violence on him, he would have done it by now. Sherlock knew he had not been kind. The data didn't lie. There's no reason to be afraid, especially since he's a man who has smirked down more than one barrel of a gun that had every intention to undo him completely. And won despite it.
He smirks now. ]
I've confirmed that this is some form of shark skin, not a ray's. By the ridiculous logic of this place, I might also be able to comfortably deduce that you can breathe underwater, or perhaps even manipulate it to some extent.