Ctrillo

I looked up the air bleed valve that doesn't look like the right piece I've googled juts about everything I can think of

I have noticed what appears to be antifreeze leaking under my car. I identified the leaking piece tonight. But I have no idea what the piece is. Anyone know and has anyone else had these piece separate like this

My car has been leaking what appears to be antifreeze. I have finally found what I believe to be the piece leaking. Does anyone know what this part is and has anyone else had the same issue ?