Blood and Bones are used in magic. Many people refrain from it though do to myths, or beliefs; others do not. I know natives, and for example local witches in my country that use (voodoo, and hoodoo) (as well as some Santeria) blood and bones. I have some Satanist friends that incorporate blood into their rituals. As well as many wiccans do to.
It can be used as offerings, or can also be used to boost certain spells. Bones can also be used for divination.