Shortly after the last ice age, pioneering organisms near the Norwegian coast founded a colony that would become, 10,000 years later, the largest of its kind on Earth.
Its members built a stony fortress that still stands today, 115 feet (35 meters) tall and 8.7 miles (14 kilometers) long, despite an environment of ceaseless cold and dark.
These hardy settlers did not spring from Stone Age Viking ancestors. They are cold-water corals whose home, the Sula Ridge Complex, is the largest deepwater reef in the world.
Relatives of sea anemones and jellyfish, cold-water corals thrive in 39° to 54°F (4° to 12°C) waters at depths ranging from 160 feet (50 meters) to 3 miles (5 kilometers).
Only in recent decades have scientists begun to regularly probe these little-known marine ecosystems, which are as rich in species as rain forests.
But recent research suggests the organisms' historic success may not continue.
In an article in the current issue of the journal Science, J. Murray Roberts of the Scottish Association for Marine Science in Oban issues a warning.
"Threats to these fragile, long-lived, and rich ecosystems are mounting." Roberts and his colleagues write.
Chief among these threats, they say, are deepwater fishing practices and the increasing acidification of the world's oceans.
"The impacts of deep-water trawling are already widespread," they write, "and effects of ocean acidification are potentially devastating."
The effects on other marine species could be equally significant, the researchers add.
Cold-water coral reefs are complex structures that provide shelter, habitat, and food to myriad species.