The PK mark is a green mystical mark identical to the glowing marks on Silver's gloves. It can always be found on the ground.
The PK mark appears in all of Silver's Action Stages and a few Town Stages. Their primary function is to create new paths for the player by using Silver's psychokinetic abilities. For this purpose, the PK mark can create several different effects, such as creating a bridge from surrounding objects that will be surrounded by a cyan aura, open doors, launching Silver or things up and unlocks cages. To activate the PK mark in gameplay, the player must use Psychokinesis directly on top of it by pressing /, or Silver may just do the animation for using it without actually activating it. In some cases, the PK mark is guarded by Iblis's Minions. After the PK mark is used once, the objects it caused to move around will be permanently frozen in their position.
- Objects that are made to be used by the PK mark cannot be grabbed by Psychokinesis even before it is activated by the player.
- Black, Fletcher (14 November 2006). "Silver the Hedgehog • Crisis City". Sonic the Hedgehog: Official Game Guide. Prima Games. p. 237. ISBN 978-0761555100.
- Black, Fletcher (14 November 2006). "Silver the Hedgehog • Crisis City". Sonic the Hedgehog: Official Game Guide. Prima Games. p. 238. ISBN 978-0761555100.