What does the phrase "terra catacombarum agnus dei" mean?

My sister got a rosary with a piece of paper in it which contained the phrase "terra catacombarum agnus dei". I think it translates to something like "earth in the catacombs," but I'm really not sure because I don't know what language its in. If you have a better translation or know what language it is in it would be a big help.