Anybody know what the markings on some of the tombstones in the graveyard are for

when i get near them i can see that when i pass my pointer near the markings the pointer turns into a hand, telling me i can use someting there.
but what

That's an easter egg leading to a dungeon. If you want to be spoiled, go here: http://www.volberding.com/Wizardry8/...meteryWalk.htm