Monday Mystery, casting number

  One of the good thing about old cast iron is that it seems like every time someone made a casting they used it as an excuse to cover it in text, so we can frequently identify patent dates as well as long-gone foundries and manufacturers. Not exactly the case here but the patternmaker did do a nice raised panel so this ESH-010 number remains clearly marked.  

  I found this while scouting for firewood candidates. I was considering a clump of deteriorating older soft maple trees growing on a rock outcropping in the woods. One tree had broken off at the roots and in among the rocks and rotting roots was this foot-long chunk of iron.  What was it doing there? That outcropping is next to a bit of valley that could possibly have been cleared as a pasture or field in the 19th century so is it a piece of farm machinery? It does vaguely resemble a ploughshare. But that region of Ontario also experienced a minor mica mining industry around the turn of the last century so maybe it's related to that.   

  Anyways, I can't quite get myself to scrap/recycle it just yet.