Ready Reference: What's Behind That Loose Stone?

A good table should really have some interesting possibilities that are both good and bad. It's with that in mind that I present today's Ready Reference table, "What's Behind That Loose Stone?", with some good and some bad things that fit behind a loose stone found in a dungeon wall. You'll also notice that there are some creatures here; I'm using a simple pattern of defining AC by armor type and giving HD. This should make it easy to convert to your system of choice. Enjoy!

What's Behind That Loose Stone? (1d12)

1. Treasure! Roll 1d12: 1-8, coins; 9-10, gems; 11, jewelry; 12, magic item. Determine as you normally would determine random room contents for the current dungeon level.
2. 1d8 spiders (AC unarmored, HD 1 hp). 25% chance that they will be poisonous.
3. 1d4 rats (AC unarmored, HD 1-2 hp). Successful attack gives 5% chance of disease.
4. A map showing this area of the dungeon. 50% chance of inaccuracies.
5. A book. This may be the diary of a long-ago dungeoneer, the rantings of the mad wizard who created the dungeon, or a religious text.
6. A skeleton. 2 in 6 chance that it is animated.
7. A passageway to elsewhere in the dungeon. The opening will have to be widened before characters can travel through it.
8. The stone conceals a hole in the floor. This may be filled with any liquid, animal, monster or anything else that the referee chooses as appropriate to dungeon level.
9. A small statue, carving or relief of a type appropriate to the dungeon's builder(s). 2 in 6 chance that it will have magical powers.
10. Ooze, slime or mold. Choose from your favorite source of monsters or generate a glop from Geoffrey McKinney's Dungeon of the Unknown.
11. A crystalline intelligence (AC chainmail, HD 2 per cubic foot). It can be contacted by spells such as ESP or other forms of mental communication. If threatened it can create an electric shock for 2d8/cubic foot (save for half).
12. The stone is one of several concealing a portal to another plane, world or dimension. It takes 1-6 turns to clear enough of the wall to go through the portal.