NYOBA DULU

 a central and often foundational part usually distinct from the enveloping part by a difference in nature 

• the core of the city

 : such as

a : the usually inedible central part of some fruits (such as a pineapple); especially : the papery or leathery carpels composing the ripened ovary in a pome fruit (such as an apple)

b : the place in a nuclear reactor where fis