First stop
"Now, tell me! Where is the treasure house?" Jiushu asked eagerly.
Lili happily started guiding her.
"Come with me." She said, guiding Jiushu through a series of confusing maze-like tunnels.
"Slowly! Let's go slowly!" Jiushu said, still obsessed with adding every species to her space.
She has always known some life forms/bacteria existed in underground caves which breathed nitrogen, hydrogen, even sulfur in some cases, however, she has never seen them directly.
Even with peripheral knowledge of such organisms, she knew very well such organisms in this much quantity are impossible to find in her own world.
They will go extinct if she doesn't keep a sample of them.
Jiushu collected them all, then kept checking to make sure she hadn't missed any.
Then, they came to a crack in a rock formation.
The merchant girl pointed at a protrusion in the cave wall.
It could be called a round button in the cave.