What is this THING?? (1980 Kawasaki kz 550)

Hey all,Bike: Kawasaki Kz 550 1980Miles, ~27,000First noticed: 2 weeks agoBike issues: non, it runs fine-ish, carbs need cleaning for sure but it runs and starts. I noticed no drop in performance from before and after I noticed this issue.I noticed a week or so ago, that the outlet encircled in red below appeared to have blown oil out of it. I think this because there was oil caked on the side of the battery and the frame opposite the outlet side (coming toward-ish the perspective of the camera). The shiny reflection you see in the battery housing is oily. There also used to be some sort of cloth plug in the outlet that is no longer there. All this leads me to believe oil popped out of there. I did overfill the bike a bit so this could make sense but I do not even know what this thing does or what it is so it is tough to say for certain.For reference on where this is in the bike, just aft of the battery housing, below the carburetor air intakes, sitting atop the engine.I looked through the Clymer manual (covering mostly the section regarding engine) and could not find any information as to what this is. Does anyone have any idea of what it is or where I should focus to find information on it? Thanks!ps. here is a video of my phone exploring around the areas for better orientationhttps://www.youtube.com/watch?v=FqDa-x50_Qk&feature=youtu.beThe thing in the red circle via /r/motorcycles https://www.reddit.com/r/motorcycles/comments/e284lo/what_is_this_thing_1980_kawasaki_kz_550/?utm_source=ifttt