Friendly_Feline: In the crypt, on the level 6, in the star-shaped "cathedral", there's a wall piece with a strange hole in it (-> screenhots). It's shaped like an ice cream cone, and when you move the cursor over it, the game says "Some kind of container..."

All I've been able to find is this:
http://www.ttlg.com/forums/showthread.php?t=60335

I've tried the golem heart, but that didn't work. Neither did Krahoz or Zohark.

edit: I've attached two screenhots, but the forum only shows one. Bug or feature?

Friendly_Feline: Found the answer in rpgdot's strategy guide for AF:
http://arwym.com/dl/Arx%20Guide_12-02-2003.pdf
(Page 52)