I am researching my great-grandfather. In a naturalization form on 1936-04-23, he listed his place and date of birth as Mishaf, Poland-Russia, 1884-08-24.

Source: https://www.ancestry.com/imageviewer/collections/2280/images/31301_168428-00442

Where is Mishaf, Poland-Russia?

I cannot find any other records referring to the existence of a town anywhere in the world called Mishaf. There's nothing on ancestry.com and there's nothing on google. Did this town ever exist? Where is it now?