Hexagonaria are a genus of colonial corals that formed calcareous reefs in shallow and warm, marine environments. They lived during the Devonian period, 350 to 400 million years back and are now extinct. Each individual member of the colony lived inside a hexagonal (six-sided) chamber from where tentacles reached out to catch food. In fossils the setting of these tentacles is visible as a radial pattern inside the hexagons. 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 of sample is 90 mm.