Created by the bees when a beekeeper forgot to insert a frame into the hive. Relevant comment:
"Frames were never really for the bees; they are for the 'farmer.' The problem with that comb is that although it's beautiful, you cannot extract the honey from it without destroying it (so the bees don't get the remains to reuse / clean out).This was in fact historically how bees were kept; the familiar wicker 'beehive' was filled with this sort of comb. In that case you not only had to destroy the comb, you most likely had to kill the queen to get the honey. (which sadly led to almost all of the bees dying, as they wouldn't even have a comb to 'requeen'). Modern hives are entirely designed to preserve as many bees as possible when harvesting."