Colors are in the eye of the beholder. For a bat-like agent there are no colors. However, for him there are sonar textures that he would also consider universal properties of the world. Colors, sounds, smells are just names describing the different ways our primate brains process sense data. Which, by the way, is an amazingly restricted subset of all possible data that can be sensed. Something similar happens with numbers. What I see as one wall, another sees a lattice of bricks (are lattices also universal properties?). What we see as one person, a virus «sees» as a population of cells with no well-defined boundary.