||Hentschel, U., Usher, K. M., and Taylor, M. W. (2006). Marine sponges as microbial fermenters. FEMS Microbiol. Ecol. 55, 167–177. doi: 10.1111/j.1574-6941.2005.00046.x p.167 left column & p.168 left column top paragraphPubMed ID16420625
||P.167 left column: "The growth habits of sponges encompass various shapes (e.g. encrusting, rope, ball, tube, barrel, vase), colours (e.g. white, yellow, green, blue, purple, brown, black) and sizes (a few millimetres to nearly two metres), and can be quite variable in response to environmental conditions (Fig. 1) (primary source)." P.168 left column top paragraph: "Because the high-microbial-abundance sponges are typically larger than their low-microbial abundance counterparts whose mesohyl is essentially devoid of bacteria, it is tempting to speculate that the presence of internal microbial biomass contributes to their larger size. The Caribbean great barrel sponge Xestospongia muta serves as a suitable example to illustrate this point (Fig. 1). As the largest known sponge species, X. muta may reach about 6–8 ft (2 m) in height. With a bacterial population density of 8 × 10^9 microorganisms per gram of wet weight a single individual, conservatively estimated at 10 kg wet weight, will hold a bacterial population size of nearly 10^14 microorganisms (U. Hentschel, unpublished data). These numbers underline the ecological relevance of sponge-associated microbiota for tropical reef ecosystems."