Sponge spicules

Sponge spicules
- Mineral elements of the skeleton that perform the support function and keep the initial form of the sponge body.

Structure
The skeletons of freshwater sponges are comprised of siliceous structures termed spicules. These spicules are well preserved in most sedimentary environments.

Types of spicules
Microscleres
Megascleres
Gemmoscleres

Time range
The earliest specimens belong to Cambrian, while their prime is estimated to continue from Ordovician period to Silurian period. Decline in development started in Devonian and continued until Triassic. Next expansion belongs to Jurassic and cretaceous periods.

Natural habitat characteristics
Nowadays most of the sponges are marine inhabitants. Corneruspongias are also found in freshwater, although not exclusively.