I was cleaning out a file cabinet in my office and found this unusual chemical reaction had occured.
I use a Fellowes monitor riser like this one:
Stuffed inside one of the legs, I had a nylon-wrapped silicon "stress ball".
The plastic leg where it comes in contact with the stress ball is breaking down, and liquifying and has pooled on the sheet of paper it was sitting on. The silicon stress-ball seems intact and the blue fabric is taut. The plastic leg is softened and has growing stress fractures as the ball trys to expand.
There is an adjacent plastic leg that was just sitting in contact with the other on, not interlocked and now they are welded together with ooze leaking out from between them.