The party doesn't need to travel very far, only 50 feet over the next ten rounds, or two minutes, in a fairly steep passage that calls for the players to sheath their weapons in order to be safe; there's no threat, and the clay soil is tough and supports you well. But the passage curls to the left and drops about 20 feet.
You cannot help but notice that the temperature has warmed somewhat unnaturally in that short time, almost like stepping outside into the sun. The smell of mown hay intensifies, and its obvious to everyone now, even before finding yourselves at the top of a natural chimney, about 8 feet across. Three quarters of the chimney space seems to be taken up by a hay-like plant, which has fixed itself solidly to the ceiling and sidewalls of the chimney, with strands about thumb-thickness, that drop into the blackness of the vertical hole. These strands are brownish grey, with no sign of greenery, but they feel lush and vibrant to the touch, indicating that they're rich with water and must be growing. The touch is so smooth that you might think it was made of corn-silk ... and dimly Maximillian seems to remember that this is an underground plant called 'tussore-weed.' The branches compress when seized and are very soft on the hands, while apparently firm and supportive.
Ahmet's Torch (including inspection of the plants): 7 minutes.