- Norwegian: steinkoraller
The stony corals are exclusively marine species. Unlike the sea anemones, they have a hard external skeleton. There exist both colonial and solitary stony corals. The skeleton of colonial species are the building blocks of the famous coral reefs found in tropical waters. However there are huge reefs in temperate and even arctic waters as well. The Norwegian oil industry has discovered, during surveys of routes for new pipelines, huge coral reefs build from Lophelia pertusa. In the Trondheim Fjord, you may find a Lophelia-reef at only 42 meters depth.
As so many other groups of cnidarians, the order Scleractinia has been subject to significant revisions since the 1990's. Traditionally, visible features were used to organize the Scleractinia's family tree. In 1996 genetic studies challenged the division of stony corals into the established suborders. MarBEF has omitted the suborders entirely, and divides the European species into 12 families.