A national emblem is a symbol that represents a nation. It may or may not appear on the national flag. It is usually something from the natural world, eg. an animal or bird, but can be any object.
The official national emblems of nations of the world in alphabetical order :
... Nigeria (and founding counterparts)
Christian Reformed Church of Nigeria[?] - (Dutch Reformed)
Reformed Church of Christ in Nigeria[?] - (Dutch Reformed)
Presbyterian ...