One type of sponge, called Hyalonema, has a tall stem comprised of long, twisted fibers that resemble glass.
An extremely distinctive species of the sponge is the glass rope sponge.
The skeleton of these sponges, which may reach heights of 6 feet and are entirely formed of silica, giving them a glass-like appearance, lacks any organ systems or tissues.
These sponges are rarely used as a shelter for fish and invertebrates and are often found in deeper seas.
Additionally, Glass Rope Sponges were once very popular wedding presents in Japan due to their sophisticated design.