After arriving at the Outer World Cave, Gu An indeed saw a Seventh-Order Medicinal Grass maturing. However, he felt it could still be left to grow, as the roots at the bottom of the plant kept growing, generating more seeds in the surrounding soil.
Gu An watched for a while. He didn't pick it, looking forward to it producing more seeds for better sustainable development.
Having already reached the Ninth Layer of the Mystic Law Spirit Immortal Realm, Gu An no longer needed to rush to harvest thousands or even tens of thousands of years of life span.
His goal was a hundred million years of life span!
As long as the overall time taken was shorter, that was fine.
If the high-rank medicinal herbs in the Outer World Cave reached maturity, he might be able to harvest tens of millions of years of life span in one go. Just thinking about it made him a little excited.