A fossil is a fossil is a fossil. This is another problem coming from the fact that words can be more precise than nature is. In nature, there is a continuum between the shells of living mollusks and fossil shells, punctuated only by death. Asking when a shell becomes fossil is like asking, "Where does blue stop and green begin?" So we have "working definitions" of slippery words. Sometimes we use specialized definitions when they are needed for particular work, like Dr. Cadee's work on taphonomy (the process of fossilization). David Campbell and others presented definitions that are of more general use. But I have to warn you that this is yet another topic on which it's best to "agree to disagree"... Andrew K. Rindsberg Geological Survey of Alabama