It does exactly what it says on the tin: adds rocks that you can throw at stuff. The code is based off that of the snowball, and was extremely simple to make (writing this page probably took longer than the mod itself, not including the times I tabbed out to watch Top Gear).
Throwing Stones: It’s a rock. You can throw it at stuff for 1.5 hearts of damage. Recipe is one cobblestone anywhere in the crafting grid. Stacks to 16.