Largest concentration of glass sponge reefs

In 1987, a scientific expedition to the seafloor off the coast of Canada’s Pacific coast discovered reefs made of glass sponge in the Hecate Strait. These ancient sponges occur globally but this was the first time they had been found forming reefs – a process last believed to have occurred during the Jurassic period. At up to 21 m in height, and around 9,000 years old, these glass sponge reefs cover at least 700 square km of the sea floor in the Hecate Strait and Queen Charlotte Sound.

Extant glass sponge reefs have not been discovered anywhere else on Earth to date.