Twin ice heart

A thumb-sized ice heart is already an immortal material, but Yu Mu Chun takes out one as large as a basin. Inside it are two conjoined pieces of heart-shaped ice: a twin ice heart, about a hundred times rarer than ordinary ice hearts. Ordinary ice hearts are the rank six peer: rank six immortal materials that can create rank six Immortal Gu. Twin ice hearts are immortal materials that can refine rank seven Immortal Gu. In that refinement the twin ice heart is only a supplementary material, not the main one. ^{ch. 860}

At Jade Pot Mountain, an ice wall holds at least a thousand blue hearts. Hei Lou Lan distinguishes twin ice hearts among those ice hearts, naming the twin form as rank seven immortal material present in quantity. Shadow Sect had spent a long time setting a Gu formation so the mountain could breed ice heart Gu; the ice hearts that form naturally there are fewer, and the wall also holds a separate ice heart Immortal Gu ready for retrieval. ^{ch. 1186}