I use a nearly identical shaped piece to hang brake calipers when I service my brakes. I made it and it is 6 inches long and about 3 across. Not a factory part. Is yours that big? Maybe a previous mechanic left his behind.
If it were a car part (and it doesn’t look like it), the only thing it could probably be is some sort of hanger for a rather large hose. The only thing that would use a hose that size is a radiator…so check to make sure none of your radiator hoses are touching something they shouldn’t be. Otherwise I think you’re in the clear.
All above seems to be correct. Everyone keeps saying this is no car part and we haven’t found any hose (including radiator) that this connects to. Just hoping the engine doesn’t fall out