http://www.treeincarnation.com/sphere_eversion.htm

The idea of a shadow universe and shadow matter make sense even in terms of simple logic. + needs -, expansion needs contraction, up needs down etc.

Imagine now for example, an atom of oxygen, well, in the shadow universe the atom could well be say, a green 2 finned dolphin (IT'S AN EXAMPLE).

How, Why? I imagine the object in Universe A is kinda put inside out and upside down etc.in Universe B (to ensure balance, equilibrium) totally inverted, you can visualize  it as an orange now having its skin on the inside and flesh on the outside, but also all its component being "inverted" in a similar way. This is just to give an approximation of what I mean since we are not talking about oranges but about scientifical non-edible stuff.