Major Jackyl wrote on Today, 00:00:

I can't even make a good guess on this one (aside from the fact that it is a cooler of some kind). Sealed system with a gas? The clear part is glass. The little nipple on the pipe looks like where it was sealed.

Just realized something. The unpainted portion of the metal flex tube seems to indicate that it pushed out at some point after assembly. Presumably it can go far enough into the glass tube that there is no gap in the paint (since there is a red ring on the glass).

Theory: Someone obtained this thing from a lab at work or school, painted it with whatever paint that had around to hide what was probably fairly ugly looking bare metal, installed it in a PC and after the years of use the radiator was clogged with dust and it was no longer capable of cooling a P4 (was it a Prescott by chance?), so it overpressured and caused the metal pipe to pop out of the glass bulb, releasing most of the cooling liquid\water. The corrosion could be from whatever moisture had been cooling in the radiator that eventually dripped down and dried\oxidized in the glass bulb.