Rugose corals (Rugosa), also called Tetracoralla, are marine corals that lived during most of the Paleozoic era and are now extinct. The chamber that formed their outer shield had the form of a horn, which had a wrinkled (rugose) exterior. They lived in shallow marine environments, forming reefs. The sample here displayed is from glacial debris in moraine deposits accumulated during the Pleistocene Ice Ages in the north Netherlands. The boulders and coarse debris in these deposits are mostly derived from Paleozoic rocks in Scandinavia. Actual width is 250 mm