You may occasionally come across frozen pieces trapped in Ice! Ice Cubes can freeze Puzzle pieces or even level goal items, such as Lockets. You'll need to break the Ice Cubes to free the item inside.
To do so, try hitting the Ice Cube with Boosters (such as Bombs or Rockets):
Or make a match with the pieces trapped within the Ice Cube:
You may have to hit an Ice Cube up to three times to fully release the item hidden inside of it.
Remember that Ice Cubes are very sturdy and can't be damaged by just making normal matches next to them: