Nature Gu Refinement Technique

Bitter shells lived in deep waters.

Taking in the sand and rocks in the water, they could melt the sediments and turn them into bitter water. If someone opened the shell and obtained this bitter water, using it to brew wine, they would get bitter shell wine. Its taste is very unique, bitter and fragrant.

Fang Yuan had once obtained a bitter shell, he opened it and used the bitter water to create bitter wine, before using that to refine the liquor worm.

Bitter shells were quite rare already, but thousand year bitter shells were even rarer, it was a good material to refine Immortal Gu.

Fang Yuan's bitter shell was a thousand year bitter shell, it was black and had circular loops of white markings, like tree rings. The alternating black and white color was very eye-catching.

Fang Yuan looked at the fire below the turtle shell, as for the thousand year bitter shell in his hand, he threw it in without looking.