Heaven and earth possessed spirit, giving birth to all kinds of precious treasures, among which crystal stones were the most common.
These crystal stones existed in places rich with spiritual energy, and over the years, through cumulative absorption of heaven and earth spiritual energy, they eventually formed different grades of spirit stones.
Because the spiritual energy within these spirit stones was relatively pure, the energy could be directly absorbed by humans, which was greatly beneficial to spiritual cultivators.
Spirit stones were classified into Heaven, Earth, Xuanhuang, and Yellow grades based on the capacity of spiritual energy they contained. At this moment, the spirit stone before Xu Nian and his companions was a Yellow-level Top-Grade Spirit Stone.
Despite being a mere Yellow-level Top-Grade Spirit Stone, the spiritual energy it contained was enough to sustain a practitioner of the Silver Moon Battle Sect level for a month of cultivation.