Magnetic nanosized assemblies with chain-like morphologies have been widely found in nature, such as magnetic bacteria, fish, birds, magnetic protists, termites and algae. This review aims to show these interesting magnetic natural biominerals, and to discuss the great efforts to artificially mimic these functional nanosized assemblies in recent years. Numerous magnetic nanowires, nanotubes and nanorings have been assembled by individual magnetic nanoparticles via several emerging general fabrication strategies, and these assemblies exhibit improved magnetic properties and unique structures, leading to wide applications in cellular manipulation, magnetic sensitive detection and therapy. (c) 2012 Elsevier Ltd. All rights reserved.