They are open. They interpenetrate and are interpenetrated by their contexts. They commingle and cohere their contexts. Our artwork which we draw here is feeble. It is feeble because it is difficult to show more than three dimensions.
Reality probably is omnidimensional.
We know reality is omniadic , but our perceptions and art which describe our reality are mostly limited to two and three dimensions. Reader, please attempt to imagine n-dimensions as apropos in your process of discovery here. For example, in our map linked to this text, you might imagine complementary omnidimensional representations of our map in all directions above, below, and around the map. Unfortunately, all of humankind's artistic endeavors are by necessity incomplete in their depictions of reality or imagined reality. It is nearly impossible to use a 2D graphic to show any intended interrelationship of actual reality and nonactual reality.