A little bit of history:
Sponge diving is the oldest known form of the art of underwater diving. Its goal is the retrieval natural sea sponges for general human use.
Most sponge that we use today are synthetic, but in the old days sponge was collected from the sea floor. Some of the finest-quality sea sponge, this ancient marine creature with a body full of pores, has always been found in the Aegean and the warm waters of southeastern Mediterranean.
It is unknown when exactly the sponge became an article of use. In ancient Greek texts, Homer and Plato mention the sponge as an object used for bathing. The ancient Greeks knew about sea sponges and their usefulness for scrubbing and cleaning purposes, and for maintaining personal hygiene. Sea sponge was also used for padding helmets and for filtering water.
Later through trading, other Europeans – like the Romans – started to use soft sea sponges for many purposes including making padding for helmets, portable drinking utensils and to filter and purify municipal water reserves. Until the invention of synthetic sponges, they were used as cleaning tools, applicators for paints and ceramic glazes, and discreet contraceptives. However, by the mid-20th century, over-fishing and climate changes had brought both the populations of sponge and the industry built around it close to extinction.
Are all species of sponge harvested?
Nope. Most sponges are too rough for general use due to their structural spicules composed of calcium carbonate or silica. But two genera, Hippospongia and Spongia, have soft, entirely fibrous skeletons. These two genera are most commonly used by humans.
Are sea sponges endangered today?
No, sponges are not on the endangered species list. However, there are threats to their habitat in some areas due to factors such as pollution, disease, exploitation, or hurricanes.