Apotheosis

The gods are untarnished by time. Timeless. Immortal. 
Right?
Well, in most ways you look at it, yes. The are only affected by the Godly Diseases, and even then very rarely. They can't be starved to death, not fully. They don't even need to sleep.
And yet, they age. In a way, at least.
As a god passes the centuries, their domains shall start to overtake their mortal body. Gods of stone often become like a statue or like a sliver of mountain that came to life. Gods of the ocean may become like the god who went through this process two centuries ago; Montiero's Joanes de Nabarres (also known as Abuelo de las Mareas).