What is this thing? Hand tool with rotatable hexagon and six different sized semicircular indents.

[MikeJhn]

Taking the different size cut outs in the end unit it obviously is for gauging or engaging into or onto different size's of material, its shape is reminiscent of a wire gauge, or a measuring instrument of some kind, it has lost its sharp edge to scrape anything with and it's oriented in the wrong direction this could have been because it has become straightened in the kitchen drawer over time, but in reality I have no idea.

 

[Yojevol]

I don't go along with any of the spaghetti or grill cleaning hypotheses. For as start any sensible spaghetti tool would be based on circular holes, not half holes and any scraping device would have sharp edges. No, I think the clue is in the semicircular recesses which are shaped to match a standard stock cupboard essential - LENTILS. It's a lentil gauge. It can be used not only to select uniform lentils from the jar, but also gauge when they are fully cooked by measuring their expansion.

Or maybe not
Brian

 

[Dovetaildave]

Does anyone know the best way to sharpen it

 

[TheUnicorn]

it is most definately for scraping clean a grill and or oven shelves, we've got one, good idea on paper, in reality pretty useless.