The following points highlight the two main skeletal elements found in sponges. The types are: 1. Spongin 2. Spicules. Skeletal Element: Type # 1. Spongin: The spongin comprises of fibres of spongin and they resemble silk in appearance. These are proteinaceous secretion of the spongioblasts and form a network. In most cases, the spongin fibres […]