The multitudinous cells that make up our bodies are miniscule factories humming with activity. The microscope reveals mitochondria, chromosomes, centrioles, granules, and a host of entities doing their own things. But even after generations have scrutinized our cells, new objects are discovered. The latest, only recognized in 1986, look like a miniature hand grenades. Called "vaults" these objects are composed of proteins and ribosomal DNA. They exist only in the cells of the higher organisms -- like us. Biologists surmise that they are important in some way but have no idea what they do.
