Following Sirius's reply, Asil's bewilderment was much greater. He thought his master would surely know, even if he didn't know what this vessel-like thing was. But unexpectedly his master didn't know what this thing was either. This caused Asil to wonder more about what exactly this vessel-like thing was.
Asil looked deep into the cave and resumed walking decisively. This time the environment was brighter so he could move faster.
After he moved a few meters more, another one of the vein-like red things appeared on the floor. This second vessel-like thing was heading deep into the cave just like the first one.
As Asil progressed, so did the number of red vessel-like things on the ground. It was also expanding as he moved deeper into the cave. The inside of the cave, which was ten men wide at first, was now about ten meters.