Different types of bread were considered a luxury among common people, although they were not uncommon. Corn bought from the merchant would be ground using a quern-stone (called "kvarnarsteinn" in Icelandic) and supplemented with dried dulse (seaweed) and lichens. Sometimes it was boiled in milk and served as a thin porridge. The porridge could be mixed with skyr to form "skyrhræringur". The most common type of bread was a pot bread called rúgbrauð, a dark and dense rye bread, reminiscent of the German pumpernickel and the Danish rugbrød, only moister. This could also be baked by burying the dough in special wooden casks in the ground close to a hot spring and picking it up the next day. Bread baked in this manner has a slightly sulphuric taste. Dried fish with butter was served with all meals of the day, serving the same purpose as the "daily bread" in Europe.