Periostracum or not periostracum ?

[diocrisseashells1000]

When i started collecting shells i never thought that shell periostracum is important, but now,..  like Dave said i started to keep one example every time i collect again a specie with periostracum, same as the operculum, They are all part of a seashell. For that "i can say it is a complete seashell".