There are no scrolls in this world, but there are crystals of various sizes, colors and qualities. Every spell has a requirement on the amount and characteristics of crystals that must be held in order for the spell to be cast, crystals which would shatter should the cast be successful. Now picture a land where crystals are scarce except for high concentrations of them in specific spots throughout the land. A number of scenarios could occur, such as benign companies selling the mined valuable for cheap, a region in constant magic-intense war zone, an area of crystals in the quicksand, or an undiscovered patch next to a town...
Foot Coral. It attatches to a foot like moss, almost gluing itself to an organism. It gets its food supply from the ground, and does not leech off the host in any way. It is not a malignant organism, and is entirely harmless. But it only grows on human feet, and even then, never on the left foot. An organism that it grows on can feel touch through the coral, but not pain. Removal of the coral is painless, but why would you want to?
Texturally, if fells like a dry, non slimy amoeba.