part of the furniture
US /pɑːrt əv ðə ˈfɜːrnɪtʃər/
UK /pɑːrt əv ðə ˈfɜːrnɪtʃər/
1.
a person or thing that has been in a place or situation for so long that they are considered a permanent, unremarkable, or indispensable feature of it
:
•
After working here for twenty years, John has become part of the furniture.
•
The old clock in the corner has been there so long it's just part of the furniture.