demosponge

From Ancient Greek δῆμος (dêmos, “common people”) + sponge, after class name Demospongiae.

demosponge (plural demosponges)

1. (zoology) A sponge of the class Demospongiae, having skeletons made of spongin fibres. [from 19th c.]
   • 1991, R. Wood, Non-Spicular Biomineralization in Calcified Demosponges, Joachim Reitner, Helmut Keupp (editors), Fossil and Recent Sponges, Springer, page 338,

     We know that at least some living calcified demosponges grow extremely slowly (0.2 mm/year Willems and Hartman 1985) and, since individuals can grow up to 1 m in diameter, are also very old (up to 5000 years).

   • 2011, Naomi E. Balaban, James E. Bobick (editors), The Handy Science Answer Book, 4th Edition, Visible Ink Press, page 466,

     Demosponges have siliceous spicules and a network of fibrous protein, spongir, that is similar to collagen. The demosponges are the source of natural household sponges, which are made by soaking dead sponges in shallow water until all the cellular material has decayed, leaving the spongin network behind.

   • 2012, Caspar Henderson, The Book of Barely Imagined Beings, 2013 edition, Granta Books, page 36:

     Demosponges, the class to which the barrel sponge belongs, are the oldest still existing multicellular animals for which there are unambiguous traces in the Cryogenian, or ‘snowball Earth’, period of the late Proterozic.