Boulder "Shrapnel" Needs To Be Smaller
I don’t know if it’s a placeholder or not (I’m guessing it is), but the remains of an exploded catapult boulder are much larger than the boulder itself! You can see this at 1:32: http://www.youtube.com/watch?v=uIieSwo6jDQ&feature
I just assumed the impact was kicking up rocks and lumps of dirt from the terrain, combined with shrapnel.
That would be a good explanation, but the rocks and lumps are the same color as the boulder, and the boulder “shrapnel” occurs whether you hit a wood or stone structure, water, or anything else…