(Because I'm working on other projects, and I can't get myself organized to actually WRITE a post.)
K and Jomama were close (see comments section) - it's a thin slice of kohlrabi. Isn't it pretty? We started growing it in the garden last year, and we've got it in two spots.
I had cooked this up and was slicing it thinly for a sort of salad/side dish thing, and I held it up to the light and thought it looked pretty. Or interesting. Or both.
Anyway, so there it is.