Confused about `git gc`

Looks like I didn't quite understand the actual role of `git gc`. I just thought that `git gc` would remove all unreferenced objects during the unpack-pack process. However, I'm not seeing the result what I was expecting from `git gc`.

I'm adding an object into the database, which is ignored by git. Then I expect the object to be removed after `git gc`. But, it's still there.

Please follow:

$ echo "/ignored_file" > .gitignore $ echo "This file is ignored by git. I'm sure that this content has never been existed in the repository before." > ignored_file $ git hash-object -w ignored_file 39cd40a92c0a92bbcbd74ec6879b4936212beebd $ ls .git/objects/ 07 39 9f b9 d0 fa info pack $ ls .git/objects/39/ cd40a92c0a92bbcbd74ec6879b4936212beebd $ git gc Counting objects: 319, done. Delta compression using up to 2 threads. Compressing objects: 100% (147/147), done. Writing objects: 100% (319/319), done. Total 319 (delta 124), reused 319 (delta 124) $ ls .git/objects/39/ cd40a92c0a92bbcbd74ec6879b4936212beebd

As you see, 39cd40a92c0a92bbcbd74ec6879b4936212beebd is still there. Shouldn't it be removed by `git gc`?

What am I overlooking?

Regards, Yakup