One specimen of Rhabdotetradium frutex Klaamann is described from the Upper Ashgillian of the Oslo Region. This is the first tetradiinaean coral recorded from Norway. The preservation of the fossil suggests an originally aragonitic skeletal composition. Comparisons with published descriptions and figures of tetradiinaean corals suggest that this group had the ability to secrete aragonite in contrast to all other early Palaeozoic corals.