User blog comment:Teridax122/What are Ultramen wearing, clothes or nothing. And what is their skin color/@comment-36271271-20180910120840/@comment-5527544-20180910213222

There are various sources which explain the markings Ultras have. Their markings are the result of their inner energy/light/biochemistry showing through the thinner parts of their skin, while the thicker parts of their skin remain silver. Also when Ultra first came to be, they were all Silver, and markings/colors appeared based on what talents said Ultras had. Red was for fighting, and blue were for scientists, and they based down those color and traits to their children.