Space filler

(I have been checking some shells list of certain dealers and in some ocassions I have seen a shell described: "Space filler"; does anybody knows actually what it means?, it is a kind of restoration?. well, that is the question: I will appreciate any answer…)

It means that the shell, though it is not the quality you might want, can "fill the space" of that missing species in your collection until a better specimen comes along.
(Answer by M. Paul Monfils via the Forum)