A vat into which rum distillers put their dunder and other leftover items such as fruit, molasses and so on. A portion of this "muck" is put into the fermenter to aid in fermentation. Commonly and improperly referred to as a Dunder Pit.
Similar to Sour Mashing.
A Muck Graveyard is where spent muck is put so that the bacterial load can be stored between cane harvesting seasons.