Spiked ball

From DwarfFortressWiki

The spiked ball is a trap component, which means that it can be mounted in weapon traps but cannot be wielded directly. While the spiked ball deals the least damage of any trap-exclusive weapon, it strikes three times, giving it the second highest potential damage of any trap component, almost as much as the legendary Large, serrated disc. Despite the slightly lower damage threshold, the critical boost possessed by the spiked ball may make it more effective than the disc against enemies with internal organs.

These have been taken from raw/objects/item_trapcomp.txt:

Name	Damage	Damage type	Number of hits	Critical boost	Wood?
Spiked Ball	100†	Pierce	3	1	Yes
† Item quality and the material the weapon is made of can change the damage points of a weapon.

For more information on weapons, trap weapon statistics, material damage effects, or item quality.