Stone and clay tablets

(There seem to be a few more tablet suggestions, but this one's different and I would really like to possibly see it added)

Made with different types of stones, these blank stone tablets would be similar to signs, except physical (and a little thicker). In order to write something on it, you need a pickaxe, and once the player finished writing it the tablet is no longer blank, like a map, and cannot be changed anymore. The block saves the writings on it and they're the same if the block is broken and placed again.

The clay tablet is a little different. First of all, you can't place it right away. When you right-click it, it opens up a UI similar to that of a sign, and you can change the writings in it however many times you'd like. You will only be able to place this block once you smelt it into a brick tablet, and by doing so, lock the info inside this tablet. When you break the brick tablet (with silk touch) it maintains whatever was written on it, and when replaced will show it again.

Because of the unique properties of the tablets, if they're presented as loot in any area they can offer a unique piece of writing to the area and present mysteries for curious players.