Legends for Ultima IV maps

Hello everyone,

I've been a fan of Ultima for most of my life...ever since Ultima IV
in my adolescence.  I recently discovered the Ultimatrix and how it
lets me check out all the dungeons and even go into the rooms and see
the layouts.  I decided that I wanted to make a tribute to the Great
Stygian Abyss of U4 within another game, and I can now do so without
having to play through all of U4 again.  (Which I did last right
before U9 came out...I even e-mailed my move count to Lord British as
I was supposed to!)  Right now the only thing holding me back is the
difference in the labelling between the Ultimatrix and other maps
floating around on the web.

For example, on the infamous Level 6 of the Abyss, on the maps that
just give a quick overview of the levels (like the one at
http://www.uo.com/archive/ftp/maps/u4/abyss.gif), there are two
"rooms" at the ends of the initial main corridors, as well as three
others around the altar at the end of this level.  But in the
Ultimatrix, these "room" are represented by red shield things, and
can't be entered.  Now, I really don't remember what these things
could be.  The orbs, fields, and fountains are already accounted for,
I believe.  And I really don't remember entering those rooms. 
(Although after the first time I know which way to go and so I haven't
been in them in what, almost 20 years?)  Are they really rooms, or are
they some sort of trap?  Does anyone here remember?

I e-mailed the Ultimatrix creator, but his site hasn't been updated
since October 2001 so I'm not optimistic about a response.  Those five
rooms, as well as the three around the starting square of level 7, are
not mapped out in the Ultimatrix, so those are the only ones I want to
know about.  Perhaps they are simple rooms with just some monsters in
them, perhaps they are more complicated than that.  I guess I will
wait to find out some general information about them before I ask for
specifics or screenshots.

Thanks in advance,

The Oneiromancer