Word for item or concept which has permanence?
Solution 1:
One term which might suit your needs is fixture:
3 : a familiar or invariably present element or feature in some particular setting; especially : a person long associated with a place or activity
—source Mirriam-Webster
Though admittedly, it implies something that has merely been established for a long period of time, and is not necessarily permanent.
Solution 2:
Such an object (or concept) could be referred to as a static.