An artifact formed in the "Whirligig" anomaly.
A deformed, reddish object made of compressed, oddly twisted, polymerized scraps of plants, soil and bones. A popular superstition among stalkers is that the strength of people perished in the anomaly is contained in the artifact.
Carrying the "Stone Blood" artifact on your belt slightly speeds up the healing process, though in result the human flesh softens up and becomes temporarily more susceptible to injury. In addition, healing requires ample nutrients, lack of which may quickly cause exhaustion. Radioactive.
Quite common, hence not very valuable. The artifact is of primary interest to scientific, primarily medical, organizations and various cult members.