The Minecraft wiki homepage associates some of its internal navigation links with icons of in-game items. Most of them are regular items like a compass or pickax, but the "Missing pages" sprite is something I don't recognize:
It doesn't look like any of the real items in the game. What is it? What's the story behind it? What makes it associated with the idea of "Missing pages"?
I tried to isolate the image file to see if its filename would shed any light on the matter, but it turned out to just be part of a spritesheet.