Board Thread:Questions and Answers/@comment-2.29.134.236-20130730151532/@comment-13413401-20130730152423

I'm assuming this was in a dimensonal dungeon. I've never run into anything like this, but ive heard of these...

Here is a link of what your problem sounds like:  http://www.minecraftforum.net/topic/1864203-the-stuff-of-nightmares-giant-red-eye-in-dimensional-dungeon-what-is-this-thing/

Quote from the dimensional dungeons mod website: "Limbo is the accumulated remains of a thousand dead worlds, timeless and infinite. Yet it is not a lifeless realm, because something old sleeps here, something that watches and waits. Think twice before you break the ancient walls within the dungeons, because whatever built them did so for a very, very good reason. There are eyes in the dark, and you are not supposed to be here."

Apparently, these a called Monoliths (found in hexxit wiki -->  http://hexxit.wikia.com/wiki/Monolith). As the page says, you should not look at them or get near them, or you will be teleported to limbo.