In article number 2302756, Guglielmo Lanzani, Francesca Di Maria, and co-workers report the intracellular formation of crystalline, fluorescent, and conductive fibers. These cell-made “bio” polymorphic materials have the unique ability to “connect” cells by penetrating the plasma membrane of neighboring cells without killing them and to conform/adapt to the cellular movement, indicating high fiber flexibility and potentially allowing for dynamic interactions and information exchange.