The rice paddle (しゃもじ, shamoji) is a flat-bladed, handled tool for transferring and mixing cooked rice. The wide, slightly concave blade mixes without crushing rice grains — a spoon would mash them.
For sushi rice
Sushi rice is seasoned in a wooden hangiri (cypress tub). The paddle is held at an angle and used in a cutting-and-fanning motion: cut through the rice vertically, fold sections over, never stir in circles. Circular motion activates gluten and makes sushi rice sticky rather than individually coated.
Non-stick surface
Modern rice paddles have a non-stick surface (typically PTFE or silicone-coated) to prevent rice adhering. Wooden paddles are traditional for sushi rice — the wood absorbs excess moisture from the rice as the vinegar is mixed in, contributing to the correct texture.