What is a cozza? Quite simply, the inexpensive but tasty shellfish we call "mussel."But it also has a fun meaning in slang, denoting an ugly girl or woman, like "dog" in American English.
It isn't intuitive to make the leap from the standard meaning to the slang, but the picture, inset, would seem to reveal that the shellfish in question does indeed leave much to be desired from the esthetic viewpoint, when you really look at it closely. It may also be that undesirable ladies may be possessive and hard to get rid of, like the mussel that firmly attaches itself to surfaces.
