What does bone lucky mean in the story tuck everlasting?

"Bone lucky," as used in the novel Tuck Everlasting, refers to the belief that someone who finds and eats a bone from a tree struck by lightning will become lucky. This belief is held by the Tuck family, who have been searching for such a bone for generations. The Tucks believe that eating the bone will grant them eternal life, as well as the ability to perform miraculous feats such as healing the sick and turning invisible.