Kachi Kachi no Mi

The Kachi Kachi no Mi, also known as the Kachi Kachi Fruit, is an anime only Paramecia type Devil Fruit that allows the body of the user to be rock hard and heat up body temperature. "Kachikachi" is the Japanese onomatopoeia for stones knocking one another to create fire. The fruit was eaten by Bear King.

Strengths and Weaknesses
This fruit allows the eater to harden the body at will, increasing defense capabilities. However, it seems that extreme force, such as a drilling bullet from the King Cannon, can pierce through it. The heating up body temperature can be also be used to increase damage done to the opponent.

This fruit doesn't seem to have any other specific weaknesses, aside the standard Devil Fruit weaknesses.

Usage
Bear King's one named attack is Hot Boiling Special (ホットボーリングスペシャル), where he heats his fist up and punches the enemy.

Trivia

 * This is the only Devil Fruit that grants two abilities that are seemingly unrelated to each other (hardening the body and heating up).