You stumble upon a statue. It is covered in cracks, and thick dirt but appears to be Nosaj the ancient Troll Healer An inscription at the bottom reads: "Be aR T E pOw r O C AoS"
(the absence of a full stop after Healer is like that in the game).
Found it in UD:2, after getting the message "You sense something of historical significance." No idea what the statue actually does.
The statue seems to be unkickable, perhaps a bug?