Found this brass thingy at a farmhouse, U.S. penny for scale. This object has three holes and there are no threads on the inside. Here are some different angles:
looks like an angled air valve or angled valve in general. a bolt should have gone in through the unthreaded open top hole to hold it down and the threaded stem would be the supply
looks like an angled air valve or angled valve in general. a bolt should have gone in through the unthreaded open top hole to hold it down and the threaded stem would be the supply
took me a minute to find it online, look for "banjo fittings" on google. in my experience they were either on compressors or something with an oil pump.