This is the underside of a DLC (diamond-like coating) coated flat tappet lifter. You can see this with your eyes, but the digital microscope allowed Dorton to take a high quality photo for reference purposes. In the center of the lifter is a pattern where the DLC coating has been worn away. The lifter must be replaced, but this pattern is just a sign of normal wear in a racing engine. But look at the larger worn area in the 8 to 12 o’clock positions. Because it looks so different and doesn’t go all the way around like the smaller pattern in the center, this is a sign that the lifter wasn’t rotating as it should which means that the corresponding cam lobe is also damaged.