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

I have a theory that the different skin colours are due to their different races just like humans before they transformed into beings of light. There are reds and there are blues. For ultras with mixed colours such as Zero, this may mean that hes a mix raced Ultra cos his dad(Ultraseven) is red and his mom(Pic Above) is blue. The silver markings may be sort of tattoos that they wish to identify themselves with.

I don't know, it's just my theory.