"What do you mean? Everything is normal!"
Anti-Matter is the material used to make any and all types of antiverses out there. It is said that those made of Anti-Matter are not aware of how unorthodox their world seems and that they in their minds acknowledge everything as flowing ever so correctly. On the outside there can be "glitches" and sorts, but they do not seem to notice it and instead their life goes on exactly as their non-anti counterpart Verse.
Take for example if we were to travel there the anti-versions of us would be no different and therefore a Mirror Paradox would begin where we would never stop mimicking ourselves to a T, however due to how their world works the non-anti counterparts would break the cycle by noticing the oddities that exist in their world where most likely this would stop the mimicking as their Anti counterparts would question them wondering what they mean by these so called strange events.