First... thank you for including a penny in the photos, to give us ID-helpers a useful size-reference for the unknown object.
There are several ID possibilities. The only one I'm 100% certain about is that it's not a civil war era artillery (nor grenade) fuze. It does closely resemble one, but there were no civil war era metal fuzes with a
solid,
flat face that had two spanner-wrench holes.
It could be a late-1800s-to-early-1900s fuze... but the "chipping" around the wrench-holes makes me lean away from that possibility. The chipping damage indicates inferior-quality metal, which the US Ordnance Department has always been
very careful to avoid. Nonetheless, I had to say "lean away from" because I can't be absolutely 100% certain that it isn't an artillery fuze from the late-1800s-to-early-1900s. You'll need to show it to somebody who has more knowledge of post-civil-war-era artillery fuzes than I do. For example, you might have success by contacting the authour of the article at:
An Introduction To Collecting Artillery Shells And Shell Casings - International Ammunition Association
He gives a link to his email address at the top of the article.
With all of that having been said... due to the wrench-hole damage, I'm suspecting the object is a valve-body from some kind of machinery. If the guy at cartridgecollectors.org is able to identify it for you with certainty, please let me know.