Original Filter - What use is it?

[victoriacoffeeroasters]

Hello all. I recently changed the power steering fluid and filter on our new to us 1980 300SD with 139K miles. The reservoir was full but the fluid was brown. I removed the old fluid down to the filter, then added some clean ATF. After running it a couple of days, I removed more fluid and repeated the process. At this time, the fluid had a fresher look. Again I removed the old fluid but this time removed the filter as well. To my surprise, it looked like an original.

So my question now it, what should I do with it?

Thanks.