The next lower prison universe has already been built. The entry point is through a black hole at the center of our galaxy. They are already tossing people into it, but its just started so most people come back up and out pretty quick. Most people on Earth, being of the troublesome type that gets sent to prison planets etc. have probably been down there once or twice already.

It seems like Hellotrobus structured the mud universe as their last act in this galaxy. The remnants of the old Hellotrobian hierarchy may be in power there now.

In the Mud Universe, space is very solid, feeling like molasses. The goal of this universe is To Persist. Note that survival implies continuing to struggle to live whereas persist implies simply hanging on as a rock or whatever. The normal tone band (i.e.. the thetan plus body range) is -8 up to 0. It is an unpleasant place.