So basically, turtle shells are only used in turtle armor and that's it. I know that turtle shells aren't very easy to come by, but seriously, they only have a single use.
Introducing the Shell Hammer
Max stack: 1
Use time: 35
Tooltip: Lobs shells, Duuuuuude!
As you can tell from the tooltip, it launches shells. Here's a sprite ->
and animated one by @Vikri
These shells would be heavily effected by gravity, and will slide across the ground similar to a boulder. Like boulders, they accelerate gradually and pierce infinitely. They can ricochet once, but will greatly decelerate and slowly stop, disappearing right after. The shell has a base damage of 50 ( may need tweaking). Shells cost no mana, but have an internal cool down of two seconds. Shells will not fire when the cursor is within “wall hammering” range.
Feel free to comment and I'm open to criticism.
Yes, the sprite is mine.