As I mentioned earlier, a lot of the "special" rooms on the upper level will be dedicated to hints about what's deeper in the dungeon. Here's a little bit of information about the Shining Trapezohedron.
164. Chief Research Assistant’s Office
This room still contains ancient steel furniture, quite rusty by now. There is a desk, chair with tattered cushions, and a short cabinet. On the stone wall next to the desk is a large white square (6’ wide by 4’ high), with several ancient inkless pens on a small shelf below it.
The desk and cabinet are empty. However, the top cabinet draw has a false back, which will be found by anybody performing a careful search. Behind the false back is a bundle of papers titled “Spectrum and Wavelength Analysis of Trapezohedron.” The papers are in an unknown scientific jargon, and the party is unlikely to make heads or tails of it.
If a player is able to read and write, and rolls a 6 on a d6 (add the number of languages the player can speak as a bonus), then he understands that the paper discusses a shining black jewel the size of a man’s fist, somewhat in the shape of a trapezohedron. The paper mentions that the angles of the jewel’s facets change depending on its orientation to the viewer, and that light reflecting from the jewel follows a discrete square wave rather than a continuous waveform.
The cult of Science in Denethix has the ability to decipher the papers if the players cannot, and would purchase them for 25 gp.
The Church of Starry Wisdom would also be greatly interested in these papers, as they refer to the Shining Trapezohedron, a jewel that can be used to communicate with their god. If they find that the party has the papers, they would do anything, up to and including murder, to retrieve the papers and determine where they came from.