Mu Jinyu saw the diamond-shaped crystal thrown by the other party and recognized it as the trading currency of the lower-level cultivators in the Canglan Realm, Source Stone!
As the name suggests, Source Stone inherently contains the Origin Qi needed for cultivation by various species, including Evil Qi, Demonic Qi, Demon Qi, Deadly Qi, Evil Qi, Spiritual Energy, Elemental Qi, Divine Qi, etc., all mixed within one crystal.
It's basically difficult to extract the pure Origin Qi needed by a single species, and it's hard to use it for cultivation, but it can still be used in setting up some formations and restrictions!
Hence, it became the trading currency among lower-level cultivators!
It's equivalent to low-grade spirit stones in the Kunlun Ruins.
