Sapsago is good cheese. It has a strong and distinctive flavor.
The common outward form of sapsago in my limited experience is a rocklike truncated cone about two inches long, roughly 1.25 inches in diameter at the base, and maybe about 0.75 inches in diameter at the narrower end. Being lithic in consistency, it is commonly grated.
Sapsago is good on pesto and also on white pizza, or for that matter any kind of pizza. It's also good on buttered bread.