The emergence of complexity is a defining feature of our planet. Moreover, complexity is ubiquitous. It is observed in inanimate and animate matter, social systems and communication protocols, and in diverse environmental networks. In each case, these systems exhibit at a fundamental level organizational properties that emerge without the intervention of any distinct organizing agent. This notion provides a formidable challenge for scientists attempting to decipher the general and specific processes responsible for complexity, and is a source of deep inspiration for those who attempt to shape and organize matter through synthetic procedures [1]. Over the past few decades, it has been realized that morphological, structural and functional complexity is often a defining characteristic of biomineralization, which generally involves temporally and spatially dependent interactions between assembling organic scaffolds and inorganic minerals [2]. Fortunately, the overwhelming variety found in biomineralization (and Nature in general) does not necessarily arise from a cumulative complexity involving excessive complication and layering of increasing numbers of components and networks, but rather from an elegant complexity where a limited number of principles and building blocks are combined in a multitude of ways to produce adaptive and evolutive structures with precise functions. This second paradigm offers hope that complexity can also be achieved in synthetic materials if the key concepts and processes can be distilled from the appropriate biological archetypes. For complex nanostructures, a good starting point is to develop experimental approaches based on principles of biomineralization, such as templated nucleation, growth and directed self-assembly. Thus, in this chapter we illustrate how unraveling the specific interactions between bio-derived templates and inorganic materials not only yields a better understanding of natural hybrid materials but also inspires new methods for developing the potential of biological molecules, superstructures and organisms as self-assembling agents for materials fabrication. 39 Nanobiotechnology II. Edited by Chad A. Mirkin and Christof M. Niemeyer