Mogura is a trident, with its three prongs tightly together. The middle prong is a full spear-shape, while the two on the sides are half-blades. Katakuri keeps the spear in his body via his Mochi Mochi no Mi when not in use.
Katakuri has shown tremendous skill with his trident, using it in conjunction with his Mochi Mochi no Mi powers. He can twist his arm with his powers to deliver a powerful drilling thrust, capable of creating deep holes in walls and shattering thick pillars, and cause a fatal wound to a human body.
Mochi Tsuki (モチ突,Mochi Tsuki?, literally meaning "Mochi Thrust"): Katakuri, while holding his spear Mogura, tightly twists his mochi arm and then untwists it while thrusting the spear forward, creating a powerful drilling stab that can easily pierce through and destroy buildings and structures. It was first used against Luffy, who barely managed to dodge it, causing the attack to instead hit a building and completely destroy it. It was later used against Luffy successfully, and created a massive, gaping wound on the side of his torso.  This is called Mochi Thrust in the Viz Manga. The name of this technique is pun on mochitsuki (餅搗き,mochitsuki?), a traditional ceremony to prepare mochi by repeatedly pounding steamed rice with a wooden mallet.