Post History
It looks like a grindstone. The two halves would be different fineness. Your friend probably had this in his cooking kit to sharpen knives. This doesn't look like it has anything to do with star...
Answer
#1: Attribution notice removed
by
System
·
2020-06-03T15:54:26Z (almost 4 years ago)
Source: https://outdoors.stackexchange.com/a/19743 License name: CC BY-SA 4.0 License URL: https://creativecommons.org/licenses/by-sa/4.0/