Physical Phantasm

A physical person or thing that exists in the physical realm, however is not socially or mentally acknowledged.

Most common example of people are those who are socially awkward, and no one talks to them, however they continue to exist in the physical realm.

Common example for objects are: pennies under the sofa, lost pencils, homework, objects under the bed; these objects exist in the physical realm however are almost never acknowledged.

Oh they're a physical phantasm, don't worry they dont' have much influence in the physical world ;)