Zou Zou no Mi, Model: Mammoth

The Zou Zou no Mi, Model: Mammoth is an Ancient Zoan-type Devil Fruit which allows the user to transform into a mammoth hybrid and full mammoth at will. "Zou" (象) means "elephant". It was eaten by Jack. According to Nekomamushi, it is the ancient form of the Zou Zou no Mi.

Strengths and Weaknesses
The full mammoth form granted by this fruit is incredibly massive, as Jack was twice as tall as Inuarashi, who is much larger than an average human. Jack can level buildings with a single swing of his trunk and leave imprints on the ground just by stepping on it with his massive feet.

However, the strength the fruit bestows is useless if the target can withstand and overcome it, as shown when Jack confronted Inuarashi and Nekomamushi. The user is also very heavy and slow in this form, being unable to avoid attacks quickly. Otherwise, the user is affected by the standard Devil Fruit weaknesses.

Usage
Jack has used this fruit to give his combat abilities a large boost; he can cause massive destruction with a single attack, and bulldoze nearly anything that gets in his way by charging forward. So far, his only attack shown has been swinging his trunk to deal damage.