Design concept - Fenrir's intruder defense system, "Labyrinth."
There is one very notable difference between the spacial distortions of the crystal and the interior of a blue police box, however. Direct exposure to the space-warping properties of this crystal is immediately fatal to a biological being, akin to being torn into a trillion pieces and then being put back together (in horror story fashion rather than Star Trek teleporter fashion. However, being within an area of Euclidean space (anything from a room to a cardboard tube whose ends are sticking out of the crystal) is perfectly safe (in the latter example's case, if the ends of a 1-meter tube were sticking out of the ends of a 50-meter diameter crystal, you could transverse 50 meters in the space of 1 meter). As such, the interior of the ship actually consists of a variable network of rooms and corridors immeasurably larger in total size than the outer size of the ship (which in wholly encased in Orihalcon plating, effectively sandwiching the crystal between an outer and inner area of normal space).
In order to permit faster travel through the areas of the ship, each passageway's entrance has a panel nearby that allows a person to connect it, via spacial distortion, to another door anywhere on the ship, provided that door is not above their security clearance or linked elsewhere. Think "Portal" and you should be able to wrap your head around the idea.
This property of the ship's interior allows for a very intricate and impenetrable defense against intrusion: The Labyrinth. When on lockdown, all passageways along the ship are linked to a vast network of 216 cube-shaped rooms, each measuring 6 acre x 6 acre x 6 acre in size. Within those rooms, the control panels for the doors are removed, with each passageway generating a random link to another door within the Labyrinth. Each room is built as a 3D maze, like a game of Pac-Man built onto a Rubik's Cube and then turned inside-out.
The reason for the cubicle nature of the rooms, and the 3D maze construction, is due to a spell-program, known as the Escher Effect, placed on them that alters gravitational pull; effectively, while in one of those rooms, "down" is whichever way you perceive it to be. This enables all 6 sides of the rooms to be used as a "floor," creating a 46,656-acre randomized maze. Add in the near-total darkness that makes seeing the other sides of the room almost impossible, and a would-be intruder could be left to wander the maze indefinitely without even realizing they're going in a giant, polydimensional circle that would give MC Escher nightmares (hence the spell-program's name). The only clue they might get is if they reach an area where they could see a fellow intruder walking along another surface; this could prove disastrous, however, if they suddenly get it in their heads that the other person is the one on the ground, at which point the Escher Effect's definition of "down" for them would change, leaving them to a potentially lethal fall to the "floor."
The only way out of the Labyrinth is to be permitted out by a member of the crew; at that point, the next exit the intruder takes will lead them back into the main hanger, the primary entrance to the ship and one of only two rooms on the ship physically linked to the outside world on its own.
On a side note, it just occurred to me that the total acreage of the Labyrinth, 46656, is 6 to the 6th power.