2004 driver side mirror question
 

I hit a cone last night with my driver side mirror. The glass is shattered, as well as hanging from a wire that's attached to the housing. My phones turned off so I can't take a picture, and it was night so I didn't get a good look at it. Basically on the back of the glass that's hanging down there's 4 plastic ridges in a circle, and two of them are broken off.

My question is if I go to a store to by a replacement mirror, will it be just a mirror to put on, or will there also be the plastic part attached to the mirror that's damaged?