Evolutionary biology is full of different and often conflicting interpretations of the fitness effects of an organism's characters. One source of these apparent conflicts is that the fitness effects can change with time, as has been captured by the phrases "historical genesis" and "current utility" in referring to them. And so it is with the word diatom in biology; it arises with one meaning and is later challenged by another meaning for dominance or commonness in usage. But competing inheritable variants -- whether genes or characters or memes -- are a norm; they are to be expected, and chance and circumstances resolve their fates or fortunes. I am no purist who advocates that diatom must mean now what it meant originally. If the current community of diatomists wishes to reorient diatom's ostensive etymological arrow to be aimed between the bottom and covering valves of the same cell -- to essentially "cut-in-half" the cell -- rather than between the sibling valves of adjacent cells, which effectively notches the filament, then I have no quarrel. But it cannot redirect where Candolle pointed that arrow in the first place, when he applied diatome to this group, and that was to the cleft between cells. Utility can and does change; an origin is cemented in an historical firmament.