The copper–carbon substrate of a transmission electron microscopy (TEM) grid reacted with aqueous silver nitrate solution within minutes to yield spectacular tree-like silver dendrites, without using any added capping or reducing reagents. These results demonstrate a facile, aqueous, room-temperature synthesis of a range of noble metal nano- and meso-structures that have widespread technological potential in the design and development of next-generation fuel cells, catalysts, and antimicrobial coatings.