What makes the skeleton of a glass sponge look like a delicate geometric network?

The skeleton of a glass sponge, which belongs to the class Hexactinellida, appears as a delicate geometric network because it is composed of siliceous spicules—needlelike structures made essentially of silicic acid.

These spicules are characteristically triaxon in form, featuring three orthogonal axes that result in six rays. When these spicules are united into a continuous, interconnected network, they create a lattice-like structure. After the sponge dies and its soft tissues decay, this remaining mineral framework retains its intricate, glass-like appearance, as seen in the Venus’s flower basket.123