Shushibaruba

Shushibaruba is an ancient monster that was awakened by Simon. It is the final boss of One Piece: Great Hidden Treasure of the Nanatsu Islands.

Appearance
In its dormant form, Shushibaruba is a translucent sphere resembling frogspawn.

In its first awakened form, it has a roundish shape with gold and purple colors, resembling a robot or machine.

In its "true form", Shushibaruba possesses octopus or squid-like tentacles and a second mouth on its torso.

Personality
Shushibaruba does not exhibit much a personality, but Simon described it as completely rejecting Devil Fruit abilities. Shushibaruba seemingly devours any Devil Fruit users it comes across and causes destruction if let out of control.

During the final phase of its battle with the Straw Hat Pirates, Shushibaruba appears to possess some remnants of Simon's consciousness and echos his ambitions.

Abilities and Powers
It has the ability to nullify Devil Fruit powers, such as Luffy's rubber powers or Chopper's transformations.

Past
Shushibaruba was originally created by an ancient civilization. In the past, its power caused an island to split into seven, creating the Nanatsu Islands. At some point, Shushibaruba became dormant on Na Island, reverting into an egg-like form. The ancient civilization then hid Na Island in the clouds, and made it so that it could only be summoned by using six treasures, which were hid across the six remaining islands.

Great Hidden Treasure of the Nanatsu Islands
In order to awaken Shushibaruba, Simon summons Na Island using the six treasures and enters the Ku Sivan temple where it lays dormant. The Straw Hat Pirates, Ko and Simon eventually reached the Nu Sivan Kuru chamber where the Shushibaruba egg was hovering above a pedestal. Simon planned to use Luffy and Chopper as bait awaken Shushibaruba, but defeated by the Straw Hats. Simon then made contact with the Shushibaruba egg, believing he could somehow become Shushibaruba himself. However, Shushibaruba merely devoured Simon and grew into its awakened form. It then did battle with both the Laotour Bandits and Straw Hat Pirates.