Carbon Freezing was a technique used to freeze supplies and occasionally living organisms in a block of dark grey Carbonite developed by Ugnaughts. In some cases, after an individual came out from Carbonite, they would have temporary lack of vision, known as Carbon sickness. Carbonite Freezing was used to get Anakin Skywalker, Obi-Wan Kenobi, Ahsoka Tano and several Clone Troopers into the Separatist stronghold, known as the Citadel.