There is only one species in this verse that are road signs, and they are alive. There are road sign plants, road sign animals, road sign fish, and road sign bacteria. There is even an exclusive type of species to the Roadsignverse called Roadsigners, and they are just road signs but they don't exist anywhere else.
The road signs are cluttered in to the max! There is literally no space that is not inhabited by some sort of road sign. This means the species are infinitely small to fit between the road signs. Road signs are very strange objects in this verse but most aren't. The Roadsignverse contains every possible type of road sign.