A method that permits the complete encapsulation of nanoparticles and nanostructures is reported by Peer Fischer and co‐workers in article number 1700234. It is demonstrated that, unlike unprotected nanoparticles that quickly corrode, nanomaterials that are chemically unstable and prone to corrosion can be encapsulated with a nanometer‐thick shell and stabilized for days in corrosive environments. Image by Alejandro Posada Boada (MPI‐IS). [Image: see text]