Eye.
The walls of the pathway had some kind of slimy substances flowing from the cracks, which colored the walls in brownish colors.
Isaac noticed that the lanterns, which illuminated the pathway in light, were quite strange. Once the slimy substances touched the fire on the lanterns, instead of subduing the fire, it made the fire stronger and made it burn much longer.
He also noticed that the blue crystals, which were used as a light in other caves, were nowhere to be seen. He had seen lanterns being used as the source of light before, but for some reason, the blue crystals were more popular ones.
Especially in the noble households. The blue crystals are used as the source of light, while the lanterns are used mostly in the dark forests as some kind of flashlight.
Isaac thought that it was quite fascinating, and he decided to study more about the usages of the blue crystals.
While in deep in his thoughts. The Players arrived at the entrances of the five paths.