Glass sponges belong to class
Glass sponges assigned to class Hexactinellida distinguished by syncytial trabecular tissues rather than cellular pinacoderm, and siliceous spicules triaxonic hexactine with six rays at right angles fused into elegant lattice forming vase or funnel shape, often deep-sea inhabitants. Classic example Venus flower basket Euplectella aspergillum illustrates intricate skeleton. Demospongiae possess monaxonic or tetraxonic siliceous spicules plus spongin fibers, Calcarea calcareous spicules mono tri tetraxonic, Sclerospongiae polyphyletic obsolete. Hexactine symmetry plus syncytium diagnose Hexactinellida among Porifera. This concept holds high importance for NEET, CBSE board, CUET and competitive examinations focusing on comparative morphology and evolutionary taxonomy within animal and fungal diversity.
Ref: Campbell Biology 12th ed. Chapter 33 Sponge Classes; Brusca & Brusca Invertebrates Hexactinellida