Hexactinellida

From Palaeos.org

o Metazoa 
`--o PORIFERA
   |--Hexactinellida 
   `--+--+--Demospongiae 
      |  `?-Archaeocyatha
      |==Sclerospongiae (polyphyletic)?
      |==Stromatoporoidea (polyphyletic)?
      `--+--Calcarea 
         `--Radiata / Eumetazoa

Hexactinellids, which are commonly called "glass sponges", construct a skeleton composed of simple to complex 6-rayed siliceous spicules, usually united in networks, the entire structure an open mesh. In some groups the spicules are fused into intricate basket-like structures.

In organization the hexactinellid sponges display the syconoid pattern (above).

They are exclusively marine, and in the modern ocean are usually found in the deep ocean (generally 450 to 900 meters, but up to 5000 meters), although earlier groups occupied shallower water. There is a very good fossil record of these organisms, going all the way back to the Cambrian period.

Credits

MAK030430