The work is a source of modern knowledge on biomineralization, biomimetics and bioinspired materials science with respect to marine invertebrates. The author gives the most coherent analysis of the nature, origin and evolution of biocomposites and biopolymers isolated from and observed in the broad diversity of marine invertebrate organisms and within their unusual structural formations. The basic format is that of a major review article, with liberal use of references to original literature. There is a wealth of new and newly synthesized information, including dozens of previously unpublished images of unique marine creatures and structures from nano- to microscale including high-resolution scanning and transmission electron micrographs. The material is organized effectively along both biological (phyla) and functional lines. The classification of biological materials of marine origin is proposed and discussed. Much of the pertinent data is organized into tables, and extensive use is made of electron micrographs and line drawings. Several modern topics e. g. "biomineralization- demineralization-remineralization phenomena", or "phenomenon of multiphase biomineralization", are discussed in details. Traditionally, such current concepts as hierarchical organization of biocomposites and skeletal structures, structural bioscaffolds, biosculpturing, biomimetism and bioinspiration as tools for the design of innovative materials are critically analyzed from both biological and materials science point of view using numerous unique examples of marine origin. This monograph reviews the most relevant advances in the marine biomaterials research field, pointing out several approaches being introduced and explored by distinct laboratories.