Spongin
From Wikipedia, the free encyclopedia
Spongin is a type of collagen protein that forms the fibrous skeleton of most organisms among the Phylum Porifera or the sponges.
Spongin does not make up spicules. Spicules can be calcareous or siliceous depending on taxinomic Class; spicules form the rigid skeleton of sponges (Phylum Porifera) as well as offer protection from predation.