Glass sponge

The Hexactinellid also known as the Glass sponge, which belong to the phylum Porifera along with other sponges.

Anatomy
The Glass sponge has no organ system or tissues. The glass sponge has no outside covering to protect them, but they do have a skeleton with a six-rayed spicules made of silica. Some of the sponges can get as tall as 10 - 30 cm tall; others more than 6 feet (1.8 m). Recently some sponges were found to have natural optic fibers that can bend in ways that would break man made fibers. Scientists study the thin organic layer that prevents cracking and hope to find how the sponges mix sodium into the fibers as they are grown in order to provide more light transmission.

Ecology
The Hexactinellid sponge is known today to live in deep waters. The 500 species today are mostly found from deep waters "200 to 2000 meters." The Hexactinellid is mostly found in Antarctica because that is where they are more abundant. The Glass Sponge eats microscopic sea creatures known as phytoplankton.

When the Glass Sponge dies, the tissue falls apart, so the skeleton which remains can rise to the surface.

One interesting fact is that the Japanese like to use the Venus Flower Basket glass sponge in their wedding ceremonies as symbols of two people joining together happily. These glass sponges capture a pair of shrimp that live inside their glass structure symbiotically, receiving protection from the glass and providing nutrients to the sponge. The sea creatures living inside the Venus Flower Basket are thought to symbolize marital happiness.

Related References

 * Hexactinellida: Life History and Ecology UC Berkeley
 * Hexactinellid Wikipedia
 * Sponge goes man-made fiber optics one better By Dan Vergano, USA TODAY. 8/21/2003.