Used fountain firework is an item. Source: Use a fountain firework. You can't buy it, but it sells for 10 Bells. Linked to Fireworks Show (1); Fireworks Show (2); Fireworks Show (3); Fireworks Show (4); Fireworks Show (5). Added in version 1.4.
Where to get it
Use a fountain firework: What remains of a fountain firework once you have set it off.
