The Achievement Block shows an achievement a player has earned in the game. Players can choose which achievement to display by wrenching the block. Punching the block will show the achievement another person has earnt.
Punching a blank Achievement Block will say "It's blank. Will no hero step up to etch it?!" When trading worlds with an etched Achievement Block, the achievement will be transferred to the new owner's name, even though the new owner does not actually have the achievement.