Ratt

Ratt (ラット) is a stand used by two rats in Part IV: Diamond is Unbreakable.

Appearance/Personality
Ratt is an insentient machine resembling a shield when it appears, and a cannon when it prepares to fire. Josuke notes to himself that it's an unusually mechanical stand for a rat, and smells of oil.

Abilities
Ratt can fire off barbed bullets, which will melt anything upon impact for it to be formed like gelatin or clay. This is very painful and would often lead to the death of one who falls victim to the bullets. Josuke has said that five or six would be enough to turn a person into a large blob, but the victim doesn't die. They can be molded into a shape, such as a cube, and continue to live (presumably unless their head is melted).

Trivia

 * Ratt is the only stand to be shared by two different people (in this case, rats) in the same Part. The only other stand to be shared by two different people is The World, shared by Dio Brando (part III) and Diego Brando from another universe (Part VII), though they can be considered the same person due to Diego being an alternate universe counterpart of Dio.