The paper says it is a > a tunnel for magnetic fields acting as if was outside the usual 3D space. I didn't understand what they meant by "acting as if it was

The paper says it is a > a tunnel for magnetic fields acting as if was outside the usual 3D space. I didn't understand what they meant by "acting as if it was outside the usual 3D space". If I did understand it then, fair enough, I'd accept the thing as a magnetic analogue of a wormhole, just as there are physically interesting hydrodynamic analogues of black and white holes. (https://arxiv.org/abs/1203.6505 https://arxiv.org/abs/1203.6505)