Examining a domain of research that has recently experienced an outburst of new structures with attractive properties, this study details how carbon and silicon are among the most important elements due to their implication in many fields, ranging from astrophysics to biology. Appraising these exotic elements and their potential interest for applications, this examination covers predicting models and the possible routes for their synthesis. Reviewing the 2D and 3D crystals based on carbon and/or silicon, and the description at the nanoscale of the new structures and complex architectures that ensue from them, this investigation offers an original perspective into these scarcely evoked structures, and is a complimentary reference to existing literature dedicated to popular nanostructures such as grapheme, nanotube, and fullerenes.