My mom would always scold my sisters and I when she saw any grains of salt that we spilled outside of our plates. Apparently, every grain of salt that a person spills and does not clean up during their lifetime is picked up after their death, with their eyelashes. These spirits with unfinished business roam our dimension looking to clean up after themselves, and cannot rest in peace until all the grains are collected. Family and friends my mom grew up with in Michoacán, Mexico, where my mom was born and raised, believed this superstition to be true. I am uncertain of its popularity outside of where she grew up, but it is one of my favorite superstitions because it prompts the person taking it in to visualize death and time.