Wooden rice bowl (or Hangiri)
Image by Feòrag NicBhrìde
Under creative common license
A hangiri is a cypress wood barrel/tub used in the sushi rice prepration process. Its main function is to make the rice cool faster due to its unique shape, and moisture obsorption ability.
Hangiris are pretty expensive, and that is probably why most home sushi makers prefer using a cheaper plastic bowl alternative. Basically, any non-metalic bowl is suitable enough for holding the rice while it cools, but nothing does it as well as Hangiri. A simple hangiri should cost around $25-50, while a professional hangiri like the ones used in restaurants cost a few hundred or more.