Looking for the genus behind the surname Rex

[Annaliv]

Hello. I'm looking for my ancestors with the surname Rex.
Marie Antonie Matthes (Born Rex) Born in 1822. Married to Moritz Christian Matthes. Born in the years 1845 to 1930. Moritz was Baker. I suspect he is from Germany.

Annaliv Victoria Schuwendt

[Britta Hansen]

Where did they live in Denmark?

Found this couple on familysearch.org tree.

However, she is listed to be born on 2 Mai 1850 Flatow, Konitz, Westpreußen, Preußen  and married Christian Moritz Matthes Nov. 1869 in Stargard, Danzig, Westpreußen, Preußen