Krusk was so cooperative while he was being questioned and Vincent couldn't help but be suspicious about it.
It could be because he's just innocent and honest or he was just trying to loosen their guard against him.
Nevertheless, Vincent was finally able to understand what was going on. Apparently, after Krusk woke up and got out of its shell, he was already alone and has been living in this cavern for quite a while.
He doesn't know how long had passed but he had basically grown up in this cavern alone.
He feeds himself by eating the fruits that this tree would bore from time to time.
Furthermore, Vincent learned that his group wasn't the first visitor who reached this place. There seems to be another humanoid creature here that warned him about humans who might cut down this tree.
Based on his description, Vincent guessed that it could be the humanoid River Dragon! This creature seems to be very injured and has been recuperating somewhere in the dungeon for a very long time!
