The act of putting something in a jar is about preservation, is about keeping that object around as it is for a long time. I have a collection of glass containers and inside that collection are objects that have been picked up and kept out of sentiment, value, or interest.
Last year, I went to Alvira PA with my aunt and picked up a groundhog skeleton. Between then and now, my attempt at curing the bones failed and it began to grow some very neat looking mold which attached it's self to a bird's nest. The bulbs were from the backyard of my old apartment. While gross in formation, I found the results to be gorgeous.