A ten-ton chunk of iron formed in the hearth area of the furnace, probably because a failure in the hearth masonry allowed molten iron to break through the side of the crucible, possibly after heat and pressure deteriorated the firebricks. Such a failure caused a costly shutdown so the hearth could be rebuilt. A salamander could also form on the side of the furnace stack if ore and limestone were not properly loaded, clogging one or more tuyeres and putting out the fire by preventing air from entering the furnace. Because a salamander was a single large piece, it had to be pulled from the furnace in one piece, a task probably requiring the combined effort of many men and oxen working with muscle power alone. Although the frequency of such failures is unknown, at least 13 salamanders like this one have been discovered at this site.