Vaults are the Protein Data Bank's molecule of the month. Nerdy, yes, but these sound kind of cool:
Vaults are composed of many copies of the major vault protein, which assembles to form a hollow football-shaped shell. The one shown here is from rat liver cells (PDB entries 2zuo, 2zv4, and 2zv5) and contains 78 copies of the protein. Inside cells, the vault also encloses a few other molecules, which were not seen in the crystal structure because they don't have a symmetrical structure inside the vault. These molecules include several small RNA molecules, a protein that binds to RNA, and an enzyme that adds nucleotides to proteins.