Mortal Gu

No matter how many mortal Gu Gu Immortals hold, that stock cannot match a single Immortal Gu. ^{ch. 460} If a mortal Gu holds only a tiny fragment of the law of heaven and earth, an Immortal Gu holds a corner of the Great Dao. ^{ch. 564}

From rank one to five, relic Gu are green copper, red steel, white silver, yellow gold, and purple crystal relic Gu. Relic Gu are mortal Gu; that line has no rank six and above Immortal Gu form. ^{ch. 469}

The text names rank five mortal Gu as a working category a Gu Immortal foundation can purchase or hold in bulk, still distinct from Immortal Gu. ^{ch. 566 ch. 599 ch. 601}

Gu Immortals possess immortal essence; a bead of it can stand as unlimited primeval essence. That lets every Gu Immortal control large numbers of mortal Gu without lacking primeval essence. ^{ch. 587} Mortal Gu are not Immortal Gu and have a limit to what they can endure; activating them without rest collapses them. When mortal Gu Masters use mortal Gu, primeval essence limits hide that flaw. When Gu Immortals activate mortal Gu, the endurance issue becomes conspicuous. ^{ch. 642}

Gu at rank six and above are covered on Immortal Gu. Gu as living tools are covered on Gu worms.