What is "tetractinellida"

Tetractinellida \Te*trac`ti*nel"li*da\, n. pl. [NL., from Gr. te`tra- tetra- + ?, ?, ray, spoke.] (Zo["o]l.) A division of Spongi[ae] in which the spicules are siliceous and have four branches diverging at right angles. Called also Tetractinellin[ae].

Tetractinellida is an order of the demosponge class. First described in 1876, this order received a new description in 2012 and replaced the two orders Astrophorida and Spirophorida, which then became sub-orders as Astrophorina and Spirophorina.