Lychniscosida
Lychniscosida is an order of sponges belonging to the class Hexactinellida and subclass Hexasterophora. They are dictyonal sponges characterized by the presence of additional struts at the nodes of the skeleton. These struts create octahedral frames, known as lychniscs.
Most members of the order are extinct, with their highest diversity as major reef builders in the Jurassic and Cretaceous periods. A few uncertain claims of Triassic lychniscosids have also been reported from China. Only three genera are still alive today: Lychnocystis, Neoaulocystis, and Scleroplegma.