Hindawi Publishing Corporation Evidence-Based Complementary and Alternative Medicine Volume 2011, Article ID 540987, 14 pages doi:10.1155/2011/540987 Research Article The largest Bio-Silica Structure on Earth: The Giant Basal Spicule from the Deep-Sea Glass Sponge Monorhaphis chuni Xiaohong Wang, 1, 2 Lu Gan, 1 Klaus P. Jochum, 3 Heinz C. Schr¨ oder, 2 and Werner E. G. M¨ uller 2 1 National Research Center for Geoanalysis, Chinese Academy of Geological Sciences, 26 Baiwanzhuang Dajie, 100037 Beijing, China 2 Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, 55128 Mainz, Germany 3 Biogeochemistry Department, Max Planck Institute for Chemistry, P.O. Box 3060, 55020 Mainz, Germany Correspondence should be addressed to Xiaohong Wang, wxh0408@hotmail.com and Werner E. G. M¨ uller, wmueller@uni-mainz.de Received 8 January 2011; Accepted 16 May 2011 Copyright © 2011 Xiaohong Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The depth of the ocean is plentifully populated with a highly diverse fauna and flora, from where the Challenger expedition (1873–1876) treasured up a rich collection of vitreous sponges [Hexactinellida]. They have been described by Schulze and represent the phylogenetically oldest class of siliceous sponges [phylum Porifera]; they are eye-catching because of their distinct body plan, which relies on a filigree skeleton. It is constructed by an array of morphologically determined elements, the spicules. Later, during the German Deep Sea Expedition “Valdivia” (1898-1899), Schulze could describe the largest siliceous hexactinellid sponge on Earth, the up to 3 m high Monorhaphis chuni, which develops the equally largest bio-silica structures, the giant basal spicules (3 m × 10mm). With such spicules as a model, basic knowledge on the morphology, formation, and development of the skeletal elements could be elaborated. Spicules are formed by a proteinaceous scaffold which mediates the formation of siliceous lamellae in which the proteins are encased. Up to eight hundred 5 to 10 μm thick lamellae can be concentrically arranged around an axial canal. The silica matrix is composed of almost pure silicon and oxygen, providing it with unusual optophysical properties that are superior to those of man-made waveguides. Experiments indicated that the spicules function in vivo as a nonocular photoreception system. In addition, the spicules have exceptional mechanical properties, combining mechanical stability with strength and stiff- ness. Like demosponges the hexactinellids synthesize their silica enzymatically, via the enzyme silicatein. All these basic insights will surely contribute also to a further applied utilization and exploration of bio-silica in material/medical science. 1. Introduction In the last decade, the phylogenetically oldest metazoan phy- lum, the Porifera (sponges) gained special interest. Mainly due to the introduction of molecular biological techniques, solid evidence was elaborated which indicated that this phylum harbors a cornucopia of new information for the understanding of the dynamics of evolutionary processes that occurred during the Earth period of Ediacara, the time prior to the Cambrian Explosion which can be dated back to approximately 540 million years ago. Furthermore, the species of this phylum are rich and valuable sources for bioprospecting, the translation of life science discoveries into practical products or processes for the benefit of the society. Sponges are the simplest multicellular animals which are grouped to the phylum Porifera according to Grant [1]. Grant [1] described these sessile, marine animals to be built just of soft, spongy (amorphously shaped) material. Later, with the discovery of the glass sponges (class Hexactinellida) [2], this view changed drastically; they were then regarded as the “most strongly individualized, radial symmetrical” entities [3]. Since their discovery, the hexactinellids were appraised as “the most characteristic inhabitants of the great depths, which rival” with the second class of Porifera, the demosponges, “in beauty” [4]. Their thin network of living tissues is supported by the characteristic skeleton, a del- icate scaffold of siliceous spicules, some of which may be fused together by secondary silica deposition to form a