...A wall?  Well, that brought all sorts of possibilities to her mind...  The quickest way to test some of them, though, involved going back down a level and picking up a good-sized rock.<br/><br/>"The aura's coming off a wall."  The halfling informed the rest of the party, as she descended down to them again.  "Hang on, I'm going to try something.  I promise it won't be anything dangerous."<br/><br/>And, after taking a little time to find a rock that she knew she'd be able to throw some distance, she ascended back up again.  Keep a good ten feet away from the wall, take aim... and throw!<br/><br/>If one of her guesses was right, that rock would pass right through the wall.  If not...  Well, at least she'd be able to cross one hypothesis off her list.