While digging on Hardian's Wall archeologists uncovered a well-worked, wooden, seat, shaped like a ring with an opening in the middle. You guessed it, they uncovered a very old toilet seat. Which is pretty cool in and of itself, because these things are few and far between. Lying their in the clay for so many years, the seat is very well preserved. It is smooth and well used. And wooden. The only one of its kind that we have.
But what is even more cool is what might lie underneath. Often, according to the site manager, Roman toilets hold all manner of artifacts. Items dropped in the abyss, tend to stay there as few braved the tunnels of despair to fetch dropped items.
So the paths to treasure continue.
That should really be where a treasure horde lies...in the latrine. It might dissuade the characters from plunging in . . . though I doubt it.