Class 2. Hexactinellida (Gr., hex=six + actin=ray) or Hyalospongiae (Gr., hyalos=glass+ spongos= sponge)

• Moderate -sized. Some reach 1 meter in length.
• Called glass sponges.
• Body shape cup, urn, or vase-like.
• Skeleton is of siliceous spicules which are triaxon with 6 rays. In some, the spicules are fused to form a lattice-like skeleton.
• No epidermal epithelium.
• Choanocytes line finger-shaped chambers.
• Cylindrical or funnel-shaped
• Found in deep tropical seas. 

Order 1. Hexasterophora

• Spicules are hexasters i.e. star-like in shape with axes branching into rays at their ends.
• Flagellated chambers regularly and radially arranged.
• Usually attached to substratum directly.
• Examples: Euplectella (Venus’ flower basket), Farnera.

Order 2.  Amphidiscophora

• Spicules are amphidiscs i.e. with a convex disc, bearing backwardly directed marginal teeth at both ends.
• Flagellated chambers are slightly different from the typical type.
• Attached to the substratum by root tufts.
• Examples: Hyalonema, Pheronema.