
This is so strange that I just thought Fred Pippin should know...
"Bog butter" refers to an ancient waxy substance found buried in peat bogs, particularly in the United Kingdom, especially in Ireland. It can be found buried inside some sort of wooden container, such as buckets, kegs, barrels, dishes and butter churns. It is a hydrocarbon of animal origin, also known as butyrellite. Until 2003 scientists and archaeologists were not quite sure of the origin of bog butter. Scientists working at the University of Bristol discovered that some samples of the "butter" were of adipose/tallow origin while others of dairy origin. It has been proposed that bog butter has been formed by food products buried in an attempt at an archaic form of refrigeration, as the peat creates a hygenic seal around the buried matter.
In Scotland, the practice of burying bog butter dates back to at least the 2nd or 3rd century. Ireland is home to the oldest recorded find of bog butter; a carved hanging bowl dating back to the 6th or 7th century AD. (From Wikipedia)
More bog butter info (because really, I needed several legitimate sites to make me believe this:
Bog Butter article24hour MuseumNew Scientist