A bone seeker is an element, often a radioisotope, that tends to accumulate in the bones of humans and other animals when it is introduced into the body. An example is 90Sr, which behaves chemically like calcium and can replace the calcium in bones. Other bone seekers include radium, samarium, and plutonium.
Bone-seeking elements are health risks and have uses in oncology.
Mel mcgrath on inspiration behind the bone seeker teaser for book break 7
References
Bone seeker Wikipedia(Text) CC BY-SA