Just a wacky idea
If a fourth dimensional being can "see" (the word "experience" seems more accurate) our entire realm at once from all angles, wouldn't that imply that all realmic things are soley comrised of the "tetrabeing"?
For the tetrabeing to experience our universe from the 4-d perspective, it would have to be infintely small (experiencing the particles that make up our realm from the inside-out, experiencing the particles that make up the particles, ect) and at the same time it would have to be at least as big as our realm.
The tetrabeing would be everything that has ever happened in all inferior dimensions. If higher dimensions are considered, the same would apply.