What is this and why would it be there?

If i was going to junk it i would, or if it milked the oil
otherwise if it's not broken don't f!@%$@$#with it!:D
I would run it, but never rebuild it.........
That's not fixed it's just had a band-aid put on it and I consider it broken, and that stuff could let loose at anytime , and maybe in pieces which would bang around in the engine and do who knows what damage.