Day 96: Shadowcat
Kitty Pryde is a mutant with the ability to pass through solid matter by passing her atomic particles through the spaces between the atoms of the object through which she is moving. In this way she and the object through which she is passing can temporarily merge without interacting, and each is unharmed when Shadowcat has finished passing through the object. This process is called "phasing" or quantum tunneling and it renders her almost completely intangible to physical touch. Shadowcat passes through objects at the same speed at which she is moving before she enters them. Since she is unable to breathe while inside an object, she can only continuously phase through solid objects (as when she travels underground) as long as she can hold her breath.