Some experts believe glass sponges are the longest-lived animals on earth;[2] these scientists tentatively estimate a maximum age of up to 15,000 years.

[3] They are more-or-less cup-shaped animals, ranging from 10 to 30 centimetres (3.9 to 11.8 in) in height, with sturdy skeletons made of glass-like silica spicules, fused to form a lattice.

[6] The body is relatively symmetrical, with a large central cavity that, in many species, opens to the outside through a sieve formed from the skeleton.

Glass sponges possess a unique system for rapidly conducting electrical impulses across their bodies, making it possible for them to respond quickly to external stimuli.

[10] Species like "Venus' flower basket" have a tuft of fibers that extends outward like an inverted crown at the base of their skeleton.

[11] This physiology is what allows for a greater flow of ions and electrical signals to move throughout the organism, with around 75% of the sponge tissue being fused in this way.

One species for example, Vazella pourtalesii, has an abundance of symbiotic microbes which aid in the nitrification and denitrification of the communities in which they are present.

In the case of Sarostegia oculata, this species almost always hosts symbiotic zoanthids, which cause the hexactinellid sponge to imitate the appearance and structure of coral reefs.

[16] Reefs discovered in Hecate Strait, British Columbia, have grown to up to 7 kilometres long and 20 metres high.

The Canadian government designated 2140 km2 of the Hecate strait and Queen Charlotte sound as a marine protected area.

[20] Although human activities only affect a small portion of glass sponges, they are still subject to the threat of climate changes.

Experiments using the species Aphrocallistes vastus have shown that increases in temperature and acidification can lead to weakened skeletal strength and stiffness.