Genealogy / Consavage, Kunczewitz, Kuncewicz family. Please help me with my ancestry... [6]

Okay so my great-grandpa, Michael Consavage (whose surname was changed at Ellis Island) immigrated here from a town called "Mosty" in Poland. Has anyone ever heard of it?? I found this out from the Ellis Island website, and I also found his original surname : Kunczewitz.

He married a woman named Sophie, but i can't find her original surname :(
Also, on the ellis island website, it said he was Russian... could it mean that maybe his parents were Russian, and then moved to Poland and had him? I am not sure.

If anyone has ever heard of this surname, please reply!

Oh, and Michael and Sophie moved to Yonkers, NY and had (I think...) 5 or 6 boys, and 1 girl. One of them happened to be my grandfather. Thank you!!!