Conch Shell Mace

This is a mace-like weapon used by Kotetsu Hagane, which he stores in a scroll and summons in battle when necessary. It resembles a conch shell with numerous sharp protrusions all over its surface and a marking in the centre that resembles an eye. Its hilt is wrapped in bandages, and a chain connects the mace to the base of the hilt. Kotetsu has been shown using it in combination with Izumo's Water Release: Starch Syrup Capturing Field that immobilises the targets' feet, making it easier to land an attack on them.

In the anime, it was shown that the protrusions on the mace can spread or integrate to form wing-like appendages that enable it to soar into the sky and evade attacks from the opponent. Even while separated, Kotetsu seems to be able to retain control of the mace's trajectory through the use of hand gestures. While it is underground, it can assume a form that has its protrusions folded against itself (likely to make it easier for it to move underground).

Trivia

 * Though unnamed in the anime and manga, this tool was named in Naruto Mobile.