The matter is not in a different universe, but in our universe. Just a different spatial plane of it. Much like a 3D structure intersected by the plane of a 2D

The matter is not in a different universe, but in our universe. Just a different spatial plane of it. Much like a 3D structure intersected by the plane of a 2D universe is surrounded "by itself" in the third spatial dimension. In such a case, the extradimensional matter lines up quite well with the observable. Mind you, I'm not a physicist, and I'm not (necessarily) proposing this as a serious model. Just an internet commenter riffing on a fun idea.