This would only be true if the signifier (“De la riva guard”) remained a separate entity from the signified (actual, physical DLR guard). It does not. While the naming convention arises from a metaphor or association, it very quickly becomes a Saussurian token of signifier/signified, with no distinction between the two.
E.g., you mention a book worm, I think of a nerdy kid reading Heinlein, not a book and a small wriggly organism.