Not in detail. The mob was named, but other than that, it was all people saying "don't go there again" and giving opinions/descriptions of the Limbo dimension rather than Monoliths. The question was only partially answered, and no one bothered to explain what Monoliths are, what they do, or why they do it. I did, in fact, notice the age of this thread. I'd imagine OP knows all about Monoliths by now, so my answer was more for the benefit of newcomers.
Monoliths are a relatively-new addition. They are the only mob naturally spawning within Dimensional Dungeons. They are intended to prevent players from cheating by breaking through the walls of traps and going around. If you remain within their line of sight and range for more than a few seconds, you will be instantly teleported to a random location in Limbo as soon as the eye opens fully. Furthermore, Limbo itself is full of them. The giant eyes you can see directly above and below you upon entering Limbo (before the surface renders) are just backdrops. Once you land, the smaller eyes all around you are the ones you have to worry about. Like the Dimensional Dungeon Monoliths, they will teleport you to another random location in Limbo. Your best shot is to check your minimap (if you have one) and try to land on Ancient Fabric (the dark parts that send you to the Overworld). Otherwise, you'll have to run and hope you're lucky enough to stumble across some Ancient Fabric within the first few teleports The Monoliths can't do damage, so they're more of a nuisance than a danger. Fortunately, you can also see them through solid objects in Tekkit Main now, thanks to a recent update. As creepy and mildly-disturbing as it is to have a dozen eyes staring at you from the walls, it's nice to know where they are. Tekkit Monoliths also no longer have a black rectangle, just an eye. Hexxit still uses the older model.
No worries, guys. I got ya covered. Took me ten minutes of testing to find the pattern and solve the puzzle (reward is three chests). Each plate affects the corresponding region of lights. The goal, of course, is to turn on all of the lights.
1
2-------3
4-------5-------6
7--------8
9
Corner plates (1, 4, 6, 9) each affect a diamond of four lights. For example, plate 1 affects lights 1, 2, 3, and 5. Plate 6 affects lights 3, 5, 6, and 8.
Edge plates (2, 3, 7, 8) affect a diagonal rectangle of six lights. For example, plate 2 affects lights 1, 2, 3, 4, 5, and 7. Plate 3 affects lights 1, 2, 3, 5, 6, and 8.
The center plate (5), as OP stated, inverts the entire grid.
1
1
1