Traits

Salt deposits sometimes collect on a saltwater leech in various shapes and forms.

Wild saltwater leeches will often find rough sand or stones to scratch these deposits off; these 'scratching posts' will often be used by several different leeches and are popular as wildlife tourist spots to view them from afar.
These may also be grown purposely, either for the purpose of selling it or for the purpose of decorating a pedigree saltwater leech. Removing the salt deposits doesn't harm the leech, but it is harmful when the salt deposits are artificially grown to cover large areas of the leeches body and especially if the salt covers its gills.
Tragically, some saltwater leeches with less sought after traits are used as salt harvest slaves until they die.