In connection with the Norwegian "Day of Geology" our national postal service requested the Geological museum (University of Oslo) for specimens that could make a good impression on stamps. Photographs from many fossil groups and minerals were provided. And guess? They picked a radiolarian on one stamp and another one as a logo on the first day cover envelope (see .pdf file). You probably all know these species. Not very common in the Norwegian Sea, though, but on print they are ok.
This is the only radiolarian stamp I know of. Does anyone else know of other radiolarian stamps?
If someone is interested, please let me know, and I can bring some stamps for sale (self cost nok. 6 = 1 US dollar) on the next Interrad meeting in New Zealand.