This is not a simulation of a single menger sponge.
Instead it is a simulation of a periodic lattice of Menger sponges.
(See "../moltemplate_files/system.lt" for details.)
To demonstrate this, several of the images in this directory show the system
after it has been replicated (twice) in the x,y,z directions. Please note that
the system is actually 8 times smaller than it appears in these images.

(Note: In VMD you can visualize the system this way by selecting the
"Graphics"->"Representations" menu option and clicking on the "Periodic" tab.)