I remember reading a sci-fi short story where the alien being had to be careful about every movement because each movement would wear him down a little bit more. He had to decide if he would save another creature crossing a river or flood at the cost of much movement which would shorten his life.
I don't remember if this was because he was made of a mineral like sandstone that rubbed off or if it was because he was so long-lived that he was considering the effect of thousands of years on his erodible body.
I think there were also wise elders in a temple that were just eroded nubs barely anything left at all, and the main character had to write his "wisdom" in the temple before he died.
Possibly the title may have been a single word like "Erosion" or "Entropy" or something like that?