The spike ball, as of most recent patches, cannot be killed through damage. Since it passes through blocks, it cannot be halted or blocked.
Spike balls only spawn in the presence of a hanging Marching Bones banner. This is a hidden secret of much of the dungeon. Most of the problem enemies only spawn under certain banners.
Have you ever noticed how many banners there are in the dungeon?
Have you ever noticed how (while the spawn rate is high everywhere) certain problem enemies seem to only appear in certain areas?
Banners work similarly to some statues. In that placing them in certain areas/biomes can cause certain enemies spawn rates to skyrocket. This can be manipulated to farm certain enemies.
The dungeon is filled with unique banners only found in the dungeon. Removing these banners will limit or eliminate the spawn potential of certain enemies, such as Spike Balls, Dark Casters, and Cursed Skulls (not sure about the dragon skull variety).
Removing the Water Candles from the dungeon also has an effect on reducing enemy spawn rates nearby. This affects all enemies (except Spike Balls, because their spawn is tied directly to the Marching Bones Banner). However, even with full torchlight, removal of all banners and Water Candles, it is impossible to eliminate the enemies' spawn completely without removing the dungeon biome (less than 40 green brick/wall in a screen area).
Best bet for avoiding Spike Balls is to identify and remove all Marching Bones banners. And all other Banners while you're at it.
Official Terraria Wiki.
By the way, most questions you ever have are much more quickly and efficiently answered by visiting the Official Terraria wiki (just google Terraria Wiki). You also usually end up with answers to questions you didn't have. I, nor my controllers would ever have survived the transition from normal to Hardmode without that site. Covers all platforms.