While Lin Yuan was observing the small squirrel, Hu Quan finished surveying the surroundings.
Hu Quan said with surprised delight, "Young Master, all the trees around are ironwood. They're even more useful than metal-type fragments when they're crushed into powder. Ironwood is also viscous and can give rocks a malleable quality when mixed in. Since we're in a forest, there should be an underground water source. This mixture of rock and ironwood will be the best waterproofing material for the outside of the underground palace. Moreover, ironwood won't rust after time like metal-type spiritual ingredients will."
Lin Yuan shook his sleeve, and the Souce Sand fell to the ground. It turned into sand particles and tunneled into the ground below Lin Yuan.
The Source Sand was no longer a Gold/Fantasy fey but a Diamond I/Fantasy II fey.
Thus, it would be easy for the Source Sand to change the environment underground.