A tea ball is used to brew loose tea.
tea ball definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
a hollow, perforated metal ball used to hold tea leaves in making tea
tea ball definition by American Heritage Dictionary
A small perforated metal ball for holding tea leaves that are to be steeped in hot water.