Just imagine if the mouth started speaking just as your party walked by.
No dungeon is complete without a statue
Or some cool architecture.
You also need some cool landscapes
How about a shrine to unknown gods?
You definitely need some flying things to swoop down and get tangled in hair.
I love the idea of sloshing through a flooded cavern and having to deal with debris in the way.
Is it rock? Is there something inside waiting to be hatched? Whatever it is don't knock it down or break it open or you'll surely regret it.
Lost tomes of knowledge.
A warrior's fate.