I only recently noticed that Nosubject.com has been offline... for some time. My apologies. The site is now back online. -- August 2017
It forms part of a subjects reality, however it is never truly known, it is mediated by the two orders of the Imaginary and the Symbolic, thus while it is present, the subject treats it as inherently Othered and alien. It is most notably discussed in Freudian theory as 'Das Ding'. This is furthered in Lacan who often cites these Uncanny objects as reminders of symbolic lack in the subjects identity formation.