@Pool vs @Hashed

I was looking through my disk as my instance was running out of disk space, when I came across a @pool directory alongside @hashed. I was not able to come across a definitive answer, but from what I’ve gathered, this “pool” is created whenever a project is forked. However, the project created from the fork is listed under the @hashed directory, so I’m not really sure what’s contained under @pool and its necessity. Can anyone enlighten me?