40M-year-old glass sponge reefs found alive off B.C. after thought extinct

Far beneath the cold waters off British Columbia, an extraordinary ecosystem is thriving in near-total darkness, a vast network of reefs made not from tropical coral, but from animals whose skeletons are built from silica, the same material found in glass.These are glass sponge reefs, and for decades scientists believed reef-building sponges of this kind had disappeared from Earth roughly 40 million years ago.Then, in 1987, Canadian scientists discovered that they were still alive.According to Fisheries and Oceans Canada (DFO), four major glass sponge reefs were discovered that year in Hecate Strait and were found to be more than 9,000 years old. The discovery revealed that an ecosystem once thought extinct had survived in the deep waters off Canada's Pacific coast.Today, these extraordinary formations are often described as the “Sea of Glass.”Reefs built by animals, not coralGlass sponges are marine animals whose intricate skeletons are made from silica.